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High-Performance Dye-Sensitized Solar Cells based on Ag-doped SnS2 Counter Electrode
Abstract
Tin disulfide (SnS2) has been considered as a prospective counter electrode (CE) material for dye-sensitized solar cells due to its good electrocatalytic property. However, its low electronic and ionic conductivities pose challenges for using it in high-performance dye-sensitized solar cells (DSSCs). Herein, doping is utilized in this study to improve the properties of SnS2 for application as the DSSC counter electrode. Ag-doped SnS2 samples with various doping amounts are prepared via a facile one-step solvothermal route. It is found that the DSSC based on 5% Ag-doped SnS2 CE demonstrates the best performance showing an impressive photovoltaic conversion efficiency (PCE) of 8.70 % which exceeds the efficiency of Pt-based DSSC (7.88%) by 10.41%, while the DSSC consisting of undoped SnS2 only exhibits a PCE of 6.47%. Such enhanced efficiency of DSSC is attributed to the effectively improved electrocatalytic activity and mixed conductivity resulted from Ag dopant. Therefore, the Ag-doped SnS2 CE proves a promising alternative to the expensive Pt CE in DSSCs and may pave a new way for large-scale production of new-generation DSSCs.
... Eg (eV) α (×10 4 cm −1 ) ρ (Ω cm) P (×10 15 Solar Energy 194 (2019) 61-73 through identifying the oxidation states of Sn, S, Cu, In and Ag from XPS analysis. 164 eV corresponds to S-Sn 2+ , S-Sn 4+ and S 0 oxidation states respectively ( Donley et al., 2002;Reddy et al., 2015;Ninan et al., 2016;Gedi et al., 2016;Cui et al., 2016;Kafashan and Blake, 2017;Ganesh et al., 2018;Mohan, 2018, 2019). Hence, the observed peak ( Fig. 2(b)) at 485.6 without any hump confirmed the presence of Sn 2+ oxidation state and peak at 161 eV attributed to S-Sn 2+ bonding, confirming the formation of single phase of SnS ( Reddy et al., 2015 Baby and Mohan, 2019). ...
... As a result, d value decreases for substitutional doping in SnS lattice due to the inverse relationship between Bragg angle (θ) and inter planar spacing (d). Tables 3-5 reveals a shift in 2θ towards higher angle side by increasing doping up to ~5%, indicates the existence of crystal lattice compression after doping, reveals the successful substitutional doping of dopant cations (Cu 2+ , In 3+ and Ag 2+ ) ( Kafashan et al., 2016;Cui et al., 2016;Rajbhandari et al., 2017;Sheini et al., 2018). Whereas further increase in doping percentage shows a shift in 2θ towards lower angle side elucidating both substitutional and interstitial doping of dopant cations ( Sinsermsuksakul et al., 2012). ...
... Similar explanation can be given for the observed decrease in XRD peak intensity with increasing the In and Ag doping up to 7.6% and 4.7% respectively. However further increase in doping (Cu > 4.8%, In > 7.6% and Ag > 4.7%), cause an increase in XRD peak intensity, indicating the formation of new nucleation centres of SnS from dopant atoms due to the effect of both substitutional and interstitial doping ( Cui et al., 2016;Gedi et al., 2016). ...
This work reports the tuning of optical and electrical properties of SnS through the incorporation of Cu, In and
Ag atom without altering its chemical and crystal structural properties, using DC-RF magnetron co-sputtering
technique with an in-situ substrate temperature of 400 °C. Doping is increased up to ~10% by varying the DC
sputtering voltage as evident from EDAX analysis. Morphological studies show the variation in surface morphology, particle size and surface roughness due to the incorporation of dopant cation into SnS lattice sites. Film
with optimized doping of ~5% resulted the substitutional doping of dopant cations (Cu2+, In3+ and Ag2+) into
SnS lattice sites which resulted an improved absorption coefficient and hall carrier concentration with a decrease
in band gap and electrical resistivity. Hall measurement studies of Cu 4.8% doped SnS film shows the p-type
conductivity with lowest electrical resistivity of 90 Ω cm and improved carrier concentration of 1017 cm−3
.
... Fig. 2(b) shows doublet at 485.6 and 494 eV correspond to Sn 3d 5/2 and Sn 3d 3/2 respectively, due to the spin orbital splitting with a binding energy separation of 8.5 eV, matching very well with the reported values (Reddy et al., 2015;Gedi et al., 2016). The reported binding energy value of Sn 3d 5/2 shows peaks at 485, 485.6 and 486.6 eV attributed to Sn 0 , Sn 2+ and Sn 4+ oxidation states respectively and S 2p 3/2 shows peaks at 161, 162 and 164 eV corresponds to S-Sn 2+ , S-Sn 4+ and S 0 oxidation states respectively (Donley et al., 2002;Reddy et al., 2015;Ninan et al., 2016;Gedi et al., 2016;Cui et al., 2016;Kafashan and Blake, 2017;Ganesh et al., 2018;Mohan, 2018, 2019). Hence, the observed peak ( Fig. 2(b)) at 485.6 without any hump confirmed the presence of Sn 2+ oxidation state and peak at 161 eV attributed to S-Sn 2+ bonding, confirming the formation of single phase of SnS (Reddy et al., 2015). ...
... The reported binding energy values of Cu 2p 3/2 shows peaks at 932, 932.5 and 933.6 eV corresponds to Cu 2+ , Cu 0 and Cu 1+ oxidation state respectively (Ninan et al., 2016;Ganesh et al., 2018). Similarly for In 3d 5/ 2 , the observed peaks at 443.2 and 444.8 eV attributed to In 0 and In 3+ oxidation states respectively and for Ag 3d 5/2 , peaks at 367.6, 368.1 and 368.2 eV corresponds to Ag 2+ , Ag 1+ and Ag 0 oxidation states respectively (Donley et al., 2002;Gedi et al., 2016;Cui et al., 2016). HR-XPS spectra of Cu 2p state ( Fig. 2(d)) shows peaks at 932 and 952 eV due to the spin orbital splitting as Cu 2p 3/2 and Cu 2p 1/2 states respectively with a binding energy difference of 20 eV which is very well matching with the reported values, validating the possibility of Cu 2+ oxidation state. ...
... Tables 3-5 reveals a shift in 2θ towards higher angle side by increasing doping up to~5%, indicates the existence of crystal lattice compression after doping, reveals the successful substitutional doping of dopant cations (Cu 2+ , In 3+ and Ag 2+ ) (Kafashan et al., 2016;Cui et al., 2016;Rajbhandari et al., 2017;Sheini et al., 2018). Whereas further increase in doping percentage shows a shift in 2θ towards lower angle side elucidating both substitutional and interstitial doping of dopant cations (Sinsermsuksakul et al., 2012). ...
... There was no discernible reduction in current density during 25 CV cycles, which signifies the stability of the counter-electrode [29]. Cui et al. revealed that the work established on 5 % Silverdoped SnS 2 counter-electrode demonstrated the PCE of 8.7 % on DSSC [30]. Despite this, the Pt-based counter-electrode shows high conversion efficiency compared to SnS 2 CEs, because SnS 2 restricts the rate of ion diffusion during the iodide/tri-iodide pair redox reaction, and its electrical conductivity is relatively small [31][32][33]. ...
... The prepared solution was filled in a 100 mL Teflon autoclave. Then the autoclave was placed in a muffle furnace allowing for a 15-hr hydrothermal reaction at 180°C [30]. Afterward, the sample solution residue was centrifuged; ethanol and DI water were utilized for washing. ...
The present work aims to investigate the electrocatalytic properties and photovoltaic power conversion efficiency (PCE) of 2D SnS2 nanoflakes pure and different transition metals (Cu, Mo, and Ni)-substituted SnS2 as cost-effective and lead-free counter-electrode (CE) for dye-sensitized solar cells (DSSC). SnS2 pure, Cu–SnS2 (CSS), Mo–SnS2 (MSS), and Ni–SnS2 (NSS) were synthesized by the facial hydrothermal method. The formation of hexagonal crystal structure and the presence of A1 g (~ 310 cm⁻¹) mode were studied using X–ray diffraction (XRD) pattern and Raman spectra, respectively. A high–resolution scanning electron microscope (HRSEM) revealed a well-defined hexagonal flake structure. A high-resolution transmission electron microscope (HRTEM) confirms the discontinuous lattice fringes. Oxidation states for the elements in a chemical compound were analyzed by X-ray photoelectron spectroscopy (XPS). The fabricated CE electrochemical characteristics were examined by cyclic voltammetry (CV) analysis with I–/ I3–-based electrolyte. The CSS sample demonstrates a higher catalytic performance and superior redox reaction, which is found from lower (0.265 V) peak-to-peak voltage separation (Epp) and higher (0.711 mA cm⁻²) cathodic current density (Ic). Also, the photovoltaic result of CSS exhibits a higher short-circuit current density (Jsc) −13.04 mA cm⁻², open-circuit voltage (Voc) −0.65 V, fill factor (FF) – 0.45, and PCE of 3.90 %.
... The two peaks at 232 eV and 229 eV reflect 3d Mo 3/2 and 3d Mo 5/2 respectively confirming the presence of Mo 4+ [46]. In Fig. 5(b) we can find two prominent peaks at 495.75 eV and 487.16 eV reflecting Sn 3d 3/2 and Sn 3d 5/2 respectively, this confirms the presence of Sn 4+ in SnS 2 [47]. Fig. 5(d) exhibits the high-resolution spectrum of S 2p. ...
... Fig. 5(d) exhibits the high-resolution spectrum of S 2p. The higher peak at 161.9 and a smaller peak at 162.7 are attributed to S 2p 1/2 and S 2p 3/2 respectively [47]. These results confirming the formation of DL-MoS 2 . ...
In this work, we have successfully synthesized pristine MoS 2 (P-MoS 2) and Sn-doped MoS 2 (D-MoS 2) by hydrothermal method for photocatalytic degradation of dye. To enhance the catalytic activities, the samples are dried by the lyophilization process. The structural and morphological analysis were done by XRD, FE-SEM, HR-TEM, UV-Vis and XPS techniques. Dye degradation experiments were conducted for Rhodamine B (RhB) using the synthesized samples under visible light irradiation to compute their photocatalytic activity. We observed that the Lyophilized Sn-doped MoS 2 (DL-MoS 2) showed enhanced photocatalytic activity than the other synthesized samples. In particular, DL-MoS 2 showed a quick and overall degradation ability for RhB in just 20 min with good reusability behaviour and photostability. The excellent photocatalytic activity of DL-MoS 2 may be due to accelerated electron transfer upon Sn doping and fast generated electron-hole pair because of a higher surface area of 127 m 2 /g. Our study revealed that the DL-MoS 2 is a good photocatalyst for the complete degradation of RhB dye.
... The two peaks at 232 eV and 229 eV reflect 3d Mo 3/2 and 3d Mo 5/2 respectively confirming the presence of Mo 4+ [45]. In Fig. 5 (b) we can find two prominent peaks at 495.75 eV and 487.16 eV reflecting Sn 3d 3/2 and Sn 3d 5/2 respectively, this confirms the presence of Sn 4+ in SnS 2 [47]. Fig. 5 (d) exhibits the high-resolution spectrum of S 2p. ...
... The higher peak at 161.9 and a smaller peak at 162.7 are attributed to S 2p 1/2 and S 2p 3/2 respectively [47]. These results confirming the formation of DL-MoS 2 . ...
In this work, we have successfully synthesized pristine MoS 2 (P-MoS 2) and Sn-doped MoS 2 (D-MoS 2) by hydrothermal method for photocatalytic degradation of dye. To enhance the catalytic activities, the samples are dried by the lyophilization process. The structural and morphological analysis were done by XRD, FE-SEM, HR-TEM, UV-Vis and XPS techniques. Dye degradation experiments were conducted for Rhodamine B (RhB) using the synthesized samples under visible light irradiation to compute their photocatalytic activity. We observed that the Lyophilized Sn-doped MoS 2 (DL-MoS 2) showed enhanced photocatalytic activity than the other synthesized samples. In particular, DL-MoS 2 showed a quick and overall degradation ability for RhB in just 20 min with good reusability behaviour and photostability. The excellent photocatalytic activity of DL-MoS 2 may be due to J o u r n a l P r e-p r o o f 2 accelerated electron transfer upon Sn doping and fast generated electron-hole pair because of a higher surface area of 127 m 2 /g. Our study revealed that the DL-MoS 2 is a good photocatalyst for the complete degradation of RhB dye.
... SnS 2 has a bandgap of 2.2 eV and it forms an S-Sn-S sandwich layered hexagonal close-packed structure (a = 3.648 Å , c = 5.899 Å and space group P3m1) has been bonded by weak Vander Waals force [12,13]. The conductivity of SnS 2 has been improved by different processes such as morphology of grown materials (nanoplate, nanotube, nanowire, nanosheets) [14][15][16][17], dopant concentration (Ag, Co, Mn, Cu, Mo, V, W) [18][19][20][21][22][23] and combining electronic conducting agent (C, CNTs, graphene) [25,26]. Previous research had found that different metal atom doped SnS 2 materials were prominently used for several applications such as solar cells [18], lithium-ion batteries [19,25], magnetic materials [20] and photocatalytic activity [21,24]. ...
... The conductivity of SnS 2 has been improved by different processes such as morphology of grown materials (nanoplate, nanotube, nanowire, nanosheets) [14][15][16][17], dopant concentration (Ag, Co, Mn, Cu, Mo, V, W) [18][19][20][21][22][23] and combining electronic conducting agent (C, CNTs, graphene) [25,26]. Previous research had found that different metal atom doped SnS 2 materials were prominently used for several applications such as solar cells [18], lithium-ion batteries [19,25], magnetic materials [20] and photocatalytic activity [21,24]. The addition of dopant elements could be easier with this layered structure, which create a wide interlayer spacing and can respond more effectively to volume changes [27,28]. ...
SnS2 nanoflakes substituted with different concentrations of Co (1, 3 and 5 %) have been synthesized by the hydrothermal process using SnCl4·5H2O, CH4N2S and Co(NO3)2.6H2O. The effect of Co on SnS2 nanoflakes were characterized by diverse analytical methods such as Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and current voltage (I–V) measurement. The XRD of pristine and Co substituted SnS2 shows a hexagonal berndtite crystal structure. The FESEM image reveals the morphology of layered nanoflakes. Elemental composition and binding state of element were studied using XPS. The Co substitution influences the SnS2 nanoflakes morphology, electrochemical and photovoltaic performance of the devices. The promising power conversion efficiency of 2.56 % was obtained with 3 % Co substituted SnS2 nanoflakes which is suitable for low-cost dye sensitized solar cells.
... Vegard's law, which states that the dopant must produce a sufficient shift in the peak position of SnS, can be used to explain the observed shift in the diffraction peak position of SnS in the absence of any dopant associated phase diffraction peaks. The substitutional and interstitial doping of dopant cations In 3+ in SnS lattice sites revealed by the shift in 2θ towards the lower angle side and higher angle side with increasing doping % is consistent with other results [44,[59][60][61][62]. Due to substitutional doping lattice parameters of host material change and that will depend upon the atomic radii of dopant material, and because of the change in lattice parameters shifting in XRD peaks can be observed [60]. ...
... Ag þ can adjust the grain size, band structure, and promote the separation of photoelectron-hole pair, which was beneficial to improve the photocatalytic efficiency. Ag doping introduced lots of holes and converted Ag x -SnS 2 directly into p-type semiconductors, which increased the charge carrier density (Cui et al. 2016). In addition, Ag doping can also increase the charge-enriched active sites and reaction sites. ...
Efficient degradation of uranium(VI) (U(VI)) in wastewater is an urgent problem because of the chemical toxicity and radiotoxicity. In this study, the Agx–SnS2 photocatalysts were compounded by a simple hydrothermal method, effectively removing U(VI) under visible light in water. Compared with SnS2, the results indicated that Agx–SnS2 would decrease the crystallinity without destroying the crystal structure. Moreover, it has excellent photocatalytic performance on the degradation rate of U(VI). Ag0.5–SnS2 exhibited a prominent photocatalytic reduction efficiency of UO22+ of about 86.4% under optical light for 75 min. This was attributed to Ag-doped catalysts, which can narrow the band gap and enhance absorption in visible light. Meanwhile, the doping of Ag promoted the separation of photoinduced carriers, so that more photogenerated charges participated in the photocatalytic reaction. The stability and reusability were verified by the cycle test and the potential photocatalytic mechanism was analyzed based on the experiment.
HIGHLIGHTS
Agx–SnS2 material was prepared by a one-step hydrothermal method.;
Ag-doped SnS2 has excellent optical adsorption capacity and a narrow band gap.;
Agx–SnS2 showed good performance in the photocatalytic reduction of UO22+.;
The mechanism of photocatalytic reduction of U(VI) by Agx–SnS2 was proposed.;
... First, the intercept of the high-frequency semicircle (left-hand side) with the X-axis represents the series resistance (R S ), which can be largely affected by the adhesion of the film with the FTO substrate [75,76]. Second, the diameter of the high-frequency semicircle (left-hand side) corresponds to the charge transfer resistance (R ct1 ) at the interface of the CE/electrolyte and the constant phase element of capacitance (CPE 1 ) corresponding to R ct1 [77]. Third, the diameter of the low-frequency semicircle represents the finite layer Nernst mass diffusion resistance (R ct2 ) within the electrolyte M. Mirzaei and M.B. ...
The luxury price and scarcity of noble platinum (Pt) hamper its commercialization in dye-sensitized solar cells (DSSCs). Hence, developing cheap, earth-abundant, and easily available electrocatalyst in lieu of Pt is of great current priority for DSSCs. Herein, core-shell structured Ni0.85[email protected]2 nanosheets anchored on carboxylic functionalized multi-walled carbon nanotubes (denoted as Ni0.85[email protected]2@MWCNTs) were prepared via two-step hydrothermal method combined with probe-sonication process. The resultant of Ni0.85[email protected]2@MWCNTs was successfully characterized by XRD, FESEM, TEM, Raman, and BET analysis. Benefiting from the larger surface areas and more electrolyte adsorption sites, the prepared Ni0.85[email protected]2@MWCNTs exhibited excellent electrocatalytic performance, electrical conductivity, and electrochemical stability when applied as the counter electrode (CE) for DSSCs. More concretely, the DSSCs assembled with Ni0.85[email protected]2@MWCNTs delivered remarkable power conversion efficiency (PCE) of 8.98%, exceeding the cell based on Pt CE (6.86%). The combination of Ni0.85[email protected]2 core-shell structure and MWCNTs provided more active sites, remarkable electric conductivity, and an admirable catalytic property toward the reduction of triiodide. This research suggests a cost-effective strategy to exploring highly effective and robust non-precious-metal CE for their potential application in next-generation energy storage and conversion devices such as DSSCs, water splitting, fuel cells, and other electrochemical applications.
... First, the intercept of the high-frequency semicircle (lefthand side) with the X-axis represents the series resistance (R S ), which can be largely affected by the adhesion of the film with the FTO substrate Wang et al., 2018). Second, the diameter of the high-frequency semicircle (left-hand side) corresponds to the charge transfer resistance (R ct1 ) at the interface of the CE/electrolyte and the constant phase element of capacitance (CPE 1 ) corresponding to R ct1 (Cui et al., 2015(Cui et al., , 2016bSilambarasan et al., 2021). Third, the diameter of the low-frequency semicircle represents the finite layer Nernst mass diffusion resistance (R ct2 ) within the electrolyte and the corresponding capacitance to R ct2 (CPE 2 ). ...
The luxury price, shortage, and instability of platinum (Pt) markedly hamper its commercialization in dye-sensitized solar cells (DSSCs). Consequently, developing an efficient alternative catalyst in lieu of noble Pt is imperative issue for the promotion of DSSCs. In this paper, a robust and electrochemically stable 3D nanocomposite comprised of amorphous ruthenium sulfide nanoparticles (RuS2 NPs), reduced graphene oxide (RGO), and functionalized multi-walled carbon nanotubes (MWCNTs) was prepared by the facile hydrothermal method and explored as a counter electrode (CE) in DSSCs. The RuS2 NPs uniformly decorated on the surfaces of the RGO/MWCNTs to form the RuS2/RGO/MWCNTs composite, which adequately inhibited aggregation of the RuS2 NPs to fully exploit its impressive electrochemical activity. Benefiting from the unexceptionable catalytic activity of RuS2 NPs in the RuS2/RGO/MWCNTs as well as superior electronic transmission channels provided by the conductive RGO/MWCNTs network, the designed DSSC with RuS2/RGO/MWCNTs exhibited a remarkable power conversion efficiency (PCE) of 13.24 % exceeding that of Pt CE (PCE: 9.53 %). Consequently, this research opens a new avenue to fabricate advanced cathode catalysts based on metallic sulfides and carbon-based materials with excellent performance for their potential application in next-generation energy storage and conversion devices such as DSSCs, water splitting, and other electrochemical applications.
... Additionally, the introduction of special elements may provide a viable approach for the immobilization of electrocatalysts from the surface of the substrate, which could allow for the preservation of the catalyzing activity and stability of CEs [21]. For instance, extensive research has been done to improve the conductivities and catalytic activity of electrocatalysts by doping them with various elements such as nickel (Ni) [22], silver (Ag) [23,24], copper (Cu) [25], and different metals (M + ) (M + = magnesium (Mg 2+ ), calcium (Ca 2+ ), strontium (Sr 2+ ), and barium (Ba 2+ )) [26]. In light of the current research findings, the photophysical and electrochemical properties of the electrocatalyst can be significantly enriched by doping it with transition elements. ...
The rational design and development of economical, high-performance, and stable counter electrodes (CE) are critical to bringing the quantum dot-sensitized solar cell (QDSSCs) from the laboratory to a practical application. In this respect, we used a two-step approach to fabricate ternary copper chalcogenide (Cu2−xSySe1−y) alloyed semiconductors onto fluorine-doped tin oxide (FTO). In the first step, the binary copper chalcogenides CuS nanostructures that are synthesized using the microwave-irradiation technique are screen-printed onto the FTO substrate and annealed in a nitrogen atmosphere to obtain Cu2−xS CE. In the second step, ternary Cu2−xSySe1−y alloyed electrocatalyst is obtained through a composition engineering approach in which the elemental Se was incorporated on the surface of as-synthesized Cu2−xS nanostructures using the drop-casting method. Compared to the pristine Cu2−xS CE, the as-synthesized Cu2−xSySe1−y CE has exhibited tunable crystal structures, compositions, morphologies. The electrochemical analysis revealed that the optimized Cu2−xSySe1−y CE has exhibited low charge transfer resistance (Rct), and excellent reduction activity to Sn²⁻ species of the polysulfide electrolyte. Accordingly, QDSSCs assembled with Cu2−xSySe1−y CE have delivered conversion efficiencies of 8.02%, which are higher than those of pristine Cu2−xS CE (7.24%). Noticeably, Cu2−xSySe1−y CE has demonstrated outstanding electrochemical stability in polysulfide redox couple, exhibiting no substantial fluctuations in either the current density or shape of the curve even after 200 continuous cyclic voltammetry (CV) cycles. Moreover, the best cell devices constructed using Cu2−xSySe1−y CE validated remarkable stability under open-air conditions, retaining <60% of the original performance after 120 h of illumination. Overall, the ease of synthesis, low cost, time efficiency, and excellent electrocatalytic characteristics of the Cu2−xSySe1−y alloyed semiconductors film demonstrated in this work make it an encouraging applicant for use as a CE material in photovoltaic applications.
... Here, 1 M iodide/polyiodide was used as the redox couple for electrochemical reaction. 57 The electrolyte solution forms a semiconducting junction between the electrodes. As SnS 2 acts as an n-type semiconductor, the electrons are majority charge carriers and holes are the minority charge carriers. ...
In the present work, we have synthesized tin disulphide (SnS2) thin films by facile, low cost, single-step hydrothermal route using various surface directing agents. The SnS2 thin films were characterized...
... However, contrary to MoS2, upon thinning down to monolayer, the band gap of 2H-SnS2 remains indirect [18]. Importantly, 2H-SnS2 shows high values of on/off current ratio in field-effect transistor devices [19], high optical absorptions [20], and indirect band gap irrespective of the layer number even down to monolayer, thus making SnS2 one of the most suitable materials for various applications. ...
After the discovery of graphene, there have been tremendous efforts in exploring various layered two-dimensional (2D) materials for their potential applications in electronics, optoelectronics, as well as energy conversion and storage. One of such 2D materials, SnS2, which is earth abundant, low in toxicity, and cost effective, has been reported to show a high on/off current ratio, fast photodetection, and high optical absorption, thus making this material promising for device applications. Further, a few recent theoretical reports predict high electrical conductivity and Seebeck coefficient in its bulk counterparts. However, the thermal properties of SnS2 have not yet been properly explored, which are important to materialize many of its potential applications. Here, we report the thermal properties of SnS2 measured using the optothermal method and supported by density functional theory (DFT) calculations. Our experiments suggest very low in-plane lattice thermal conductivity (\k{appa} = 3.20 +- 0.57 W m-1 K-1) and cross-plane interfacial thermal conductance per unit area (g = 0.53 +- 0.09 MW m-2 K-1) for monolayer SnS2 supported on a SiO2/Si substrate. The thermal properties show a dependence on the thickness of the SnS2 flake. Based on the findings of our DFT calculations, the very low value of the lattice thermal conductivity can be attributed to low group velocity, a shorter lifetime of the phonons, and strong anharmonicity in the crystal. Materials with low thermal conductivity are important for thermoelectric applications as the thermoelectric power coefficient goes inversely with the thermal conductivity.
... For example, p-type SnS NWs have been synthesized and demonstrated excellent optoelectronic performance in our previous work [7]. SnS 2 is an n-type semiconductor with bandgap ranging from 2.1 to 2.4 eV [11,15], and SnS 2 -based nanostructures have been demonstrated to show broad prospects in field-effect transistors [14,15], battery materials [16,17], photodetectors [12,13,18], gas sensors [19], and solar cells [20,21]. Most studies on SnS 2 nanostructures mainly focus on quantum dots [22], nanosheets [12,13,18] and thin films [23,24], but very limited study on SnS 2 NWs. ...
Tin sulfide semiconductor nanowires (NWs) have been widely investigated for photodetection applications because of their good optical and electrical properties. Herein, we synthesized n-type SnS 2 NWs and then fabricated SnS 2 NW photodetectors with a ferroelectric polymer side-gate. The strong electric field induced by ferroelectric polymer can effectively suppress the dark current and improve the detectivity in SnS 2 NW photodetectors. The photodetectors after polarization depletion exhibit a high photoconductive gain of 4.0 × 10 ⁵ and a high responsivity of 2.1 × 10 ⁵ A W ⁻¹ . Compared with devices without polarization depletion, the detectivity of polarization-depleted photodetectors is improved by at least two orders of magnitude, and the highest detectivity is 1.3 × 10 ¹⁶ Jones. Further, the rise and fall time are 56 and 91 ms respectively, which are about tens of times faster than those without polarization depletion. The device also shows a good spectral response from ultraviolet to near-infrared. This study demonstrates that ferroelectric materials can enhance optoelectronic properties of low-dimensional semiconductors for high-performance photodetectors.
... Combined with the references on the subject of doping [39][40][41], it can be inferred that the incorporation of In element promotes the formation of Sn-In-S or In-S bonds, thus facilitating the transfer of electrons from the doped In to Sn and S. In-O-ultrathin-SnS 2 . As shown in Fig. 4a that the current density of ...
The unique two-dimensional structure of ultrathin nanomaterials provides an ideal platform for regulating properties at the atomic level. Herein, gradually thinning method combined with dual-ion co-substitution strategy realizes the evolution of micron-sized bulk ZnSn(OH)6-precursor (2 μm) to functionalized In-O-ultrathin-SnS2 nanosheets (3 nm). The In-O-ultrathin-SnS2 achieves formate Faraday efficiency (FEHCOO-) of 88.6% and partial current density (jHCOO-) of 22.7 mA cm⁻² at a moderate overpotential of 1.0 V for CO2 electrocatalytic reduction, which demonstrates a remarkable improvement in comparing with that of the unadorned ultrathin-SnS2 (FEHCOO- = 17.5%, jHCOO- = 9.4 mA cm⁻²). Density functional theory calculations demonstrate that the superior activity of In-O-ultrathin-SnS2 is attributed to the synergistic effect among oxidized Sn and the adjacent In sites in reducing the free energy of the key intermediates formation and accelerating the charge transfer rate.
... The high short-circuit current density of the perovskites results from the effective electron collection of the 2D SnS 2 nanosheets from the perovskite layer and fast electron transport to the FTO. 260 The Ag-doped SnS 2 counter electrode for dye-sensitized solar cells showed an impressive photovoltaic conversion efficiency of 8.70%. The enhanced efficiency is attributed to the effectively improved electrocatalytic activity and mixed conductivity resulting from the Ag dopant. ...
The tin sulfide (SnxSy) class of materials has attracted tremendous research interest in recent years owing to their intriguing physicochemical properties. Their inimitable optical, electronic, and mechanical properties open up windows for a broad range of promising applications. The precise design and tuning of the crystal phase, size, thickness, and composition holds excellent potential for utilizing them as crucial components of advanced devices. In this review, we explore the recent progress in their synthesis, properties, and applications. Initially, we outline the SnxSy class of materials briefly and discuss the recent developments in their phase and crystal dependent physicochemical properties. Numerous strategies have been portrayed for the preparation of single- to multi-layer, zero dimension to three dimension, and nano-sized to micro-sized materials. In-depth information on synthesis methods has been explored under the top-down and bottom-up approaches. The review includes the properties and synthesis of tin sulfides and also delivers exciting progress in various fields of applications. Finally, the prospects and opportunities in these exciting fields are discussed, based on their current progress.
... In addition, the diffraction peak corresponding to (004) plane of CCTS-2 slightly shifts toward higher Bragg angle, while the peaks corresponding to (204) and (103) planes are shifted toward lower angle when compared with CCTS-1. This shifting in peak positions toward the opposite direction to one another in CCTS-2 indicate a balancing of stress and strain at the grain boundaries, which can be occurred due to the deformation of internal axis in one direction [12][13][14]. ...
Herein, structural and optical properties of Cu2MSnS4 (M = Co and Fe) nanoparticles synthesized by ultrasonic-assisted sol–gel method using two different solvents are studied. XRD study shows the nanoparticles with tetragonal kesterite structure and crystallite size in the range of 4–7 nm. XPS study reveals the oxidation state of constituent elements. The optical band gap and textural properties like surface area and pore size are estimated through UV–VIS–NIR and nitrogen adsorption–desorption analyses. Quaternary Cu2MSnS4 (M = Co & Fe) nanoparticles were successfully synthesized using two different solvents by ultrasonic assisted sol–gel method.The as-synthesized material shows good optical response from UV to NIR region of the solar spectrum.The good optical response along with its large BET surface area to volume ratio suggests that the synthesized material can have potential application as an absorber layer in a thin-film solar cell. Quaternary Cu2MSnS4 (M = Co & Fe) nanoparticles were successfully synthesized using two different solvents by ultrasonic assisted sol–gel method. The as-synthesized material shows good optical response from UV to NIR region of the solar spectrum. The good optical response along with its large BET surface area to volume ratio suggests that the synthesized material can have potential application as an absorber layer in a thin-film solar cell.
... Recent studies demonstrated that metal-ion doping is an effective approach to manipulate the physical and chemical properties of metal sulfide CEs by altering their crystal structures and morphologies by introducing defects into the materials [47,48]. Extensive studies have been carried out to increase the conductivities and carrier concentrations of SnS thin films using different dopants such as Ag, Al, Sb, In, and Fe [49][50][51]. Recent research results indicate that the doping with a less resistive element such as Cu is quite effective for the improvements in photophysical and electrochemical properties of metal sulfide thin films [52][53]. Inspired by the significant experimental results of the previous studies, we evaluate the potential of a Cu-doped SnS thin film for use as an efficient CE material to improve the photovoltaic performances of QDSSCs. ...
High charge transfer resistance at the interface between counter electrodes (CEs) and sulfide/polysulfide based electrolytes is responsible for the low photoelectrochemical performance of quantum dot sensitized solar cells (QDSSCs). Here, for the first time, we fabricated highly electrocatalytic and stable Cu-doped SnS CEs by inexpensive chemical bath deposition (CBD) method, to control the interfacial charge transfer resistance in QDSSCs and increase their photovoltaic performance. TiO2/CdS/CdSe/ZnS photoanodes and an aqueous polysulfide electrolyte were used to fabricate the QDSSCs with CEs. The QDSSCs with a 10% Cu-doped SnS CE achieved an outstanding conversion efficiency of 4.07% under standard simulated AM 1.5 illumination, exceeding that of a cell with an undoped SnS CE (2.80%). The surface morphologies of SnS CEs with different Cu contents were significantly different. The voids between SnS nanoparticles deposited on fluorine-doped tin oxide (FTO) substrate were reduced upon the uniform distribution of Cu dopants. The Cu-doped SnS CE had significantly improved electrocatalytic activity for catalysis during the reduction of electrolyte, low charge transfer resistance at the CE/electrolyte interface, and fast electron transport from SnS surface to the electrolyte to regenerate the redox couple. These findings may inspire the design of efficient CEs for the large-scale production of next-generation QDSSCs.
In this work, a label-free electrochemical immunosensor using tin sulfide/nickel cobalt metal-organic frameworks (SnS2/NiCo MOFs) was established for the sensitive etection of cortisol. First, SnS2/NiCo MOFs were synthesized by doping SnS2 with NiCo MOF nanocubes by a hydrothermal method. Then, gold nanoparticles (AuNPs) were grown in situ on SnS2/NiCo MOFs for electrochemical detection. The use of SnS2/NiCo MOFs promoted the electron transfer rate of AuNPs and enhanced the electrochemical sensing performance of AuNPs@SnS2/NiCo MOFs-modified electrodes. The large specific surface area of AuNPs@SnS2/NiCo MOFs provides more active sites for antibody loading. After the prepared immunosensor was incubated with the target analyte, cortisol, the electron transfer impedance increased and the amperometric response decreased, thus establishing a highly sensitive immunosensing method. The sensor had a linear range of 100 fg/mL to 100 ng/mL and a low detection limit of 29 fg/mL. The sensor showed good accuracy and practicability and could be used for the determination of cortisol in saliva.
Developing efficient heterojunction electrocatalysts and uncovering their atomic‐level interfacial mechanism in promoting sulfur‐species adsorption‐electrocatalysis are interesting yet challenging in lithium‐sulfur batteries (LSBs). Here, multifunctional SnS2‐MXene Mott–Schottky heterojunctions with interfacial built‐in electric field (BIEF) are developed, as a model to decipher their BIEF effect for accelerating synergistic adsorption‐electrocatalysis of bidirectional sulfur conversion. Theoretical and experimental analysis confirm that because Ti atoms in MXene easily lost electrons, whereas S atoms in SnS2 easily gain electrons, and under Mott–Schottky influence, SnS2‐MXene heterojunction forms the spontaneous BIEF, leading to the electronic flow from MXene to SnS2, so SnS2 surface easily bonds with more lithium polysulfides. Moreover, the hetero‐interface quickly propels abundant Li+/electron transfer, so greatly lowering Li2S nucleation/decomposition barrier, promoting bidirectional sulfur conversion. Therefore, S/SnS2‐MXene cathode displays a high reversible capacity (1,188.5 mAh g−1 at 0.2 C) and a stable long‐life span with 500 cycles (≈82.7% retention at 1.0 C). Importantly, the thick sulfur cathode (sulfur loading: 8.0 mg cm−2) presents a large areal capacity of 7.35 mAh cm−2 at lean electrolyte of 5.0 µL mgs−1. This work verifies the substantive mechanism that how BIEF optimizes the catalytic performance of heterojunctions and provides an effective strategy for deigning efficient bidirectional Li‐S catalysts in LSBs. The authors design a SnS2‐MXene Mott–Schottky heterojunction catalyst with built‐in electric field (BIEF), and the formation mechanism of BIEF, BIEF effect, and atomic‐level manipulation mechanism for accelerating adsorption‐electrocatalysis of bidirectional sulfur conversion are uncovered. The obtained S/SnS2‐MXene cathode displays a long‐life span with 500 cycles and a large areal capacity at lean electrolyte.
Dye-sensitized solar cell (DSSC) is considered as an excellent indoor photovoltaic (PV) technology because it shows better performance even in scattered indoor light, low cost, high flexibility, semi-transparency in nature and availability of variety of colors. Counter Electrode (CE) is one of a crucial component in DSSC as it collects electrons from the external circuit and also act as a catalyzer towards iodide/triiodide (I−/I3−) redox couple in the electrolyte. Platinum (Pt) noble metal is commonly used as a CE material for designing DSSC. But, due to high cost and corrosion activity towards the I−/I3− reduction process, Pt lost its application. Hence, in order to develop a Pt-free CE, several new materials have been explored to fabricate highly efficient DSSC. In this review, the recent progress of binary and ternary transition metal chalcogenides (TMC) and their composites as an effective CE to replace expensive Pt metal CE in DSSC are discussed.
Tin disulfide (SnS2) is an emerging 2D‐layered metal dichalcogenide with promising application potential for highly sensitive and fast‐response‐speed photodetectors. However, SnS2‐based photodetectors still have drawbacks that limit their practical and commercial applications. Herein, an effective route is proposed for constructing SnS2/indium‐doped SnS2 homostructures to improve photodetector performance. Vertical SnS2/Sn0.991In0.009S2 homostructures and photodetectors based on these homostructures were fabricated via a polydimethylsiloxane‐assisted dry‐transfer method. The photodetectors exhibit excellent performance, including a high photoresponsivity of up to 271.7 A W−1, high normalized detectivity of up to 2.13 × 1012 cm Hz1/2 W−1, and fast response time of ≈10 ms. The pseudo‐built‐in electrical field of the SnS2/Sn0.991In0.009S2 homostructure results in the superior performance of the photodetectors based on this material compared to that based on individual SnS2 and Sn0.991In0.009S2 thin layers, most 2D materials, and commercial photodetectors (e.g., THORLABS FD11A Si, and FGA01 InGaAs). This study provides a facile and effective approach to enhance the performance of SnS2‐based photodetectors and paves the way for future applications of photodetectors based on SnS2 and other 2D materials. SnS2/Sn0.991In0.009S2 homostructures are prepared via mechanical exfoliation and polydimethylsiloxane‐assisted dry‐transfer from chemical vapor transport grown high‐crystallinity bulk crystals. A photodetector based on the SnS2/Sn0.991In0.009S2 homostructure is fabricated and evaluated, exhibiting excellent performance with a high photoresponsivity of up to 271.7 A W−1, excellent normalized detectivity of 2.13 × 1012 cm Hz1/2 W–1, and short response time of 10 ms under 405 nm laser illumination.
Tin(IV) sulfide (SnS2) decorated by different levels of Au nanoparticles was successfully prepared by the solvothermal method, followed by in situ reductions. The Au nanoparticles were uniformly coated on the surface of SnS2 sheet flowers. Further gas-sensing test results show that the modified Au nanoparticles greatly enhanced the NO2-sensing performances of SnS2 sheet flowers. In particular, the sensor based on 0.5 wt% Au-SnS2 exhibited a high response of 13.2 toward 2 ppm NO2, which was 10.047-fold higher than that of the pristine SnS2 sensor at near room temperature (60 °C). Meanwhile, it also shows a curtate response and recovery time (45/148 s) and improved selectivity toward NO2 in comparison with pristine SnS2. The enhanced sensing mechanism of composites was probably due to the electronic and chemical sensitization of Au nanoparticles. The sensor based on 0.5 wt% Au-SnS2 presents huge advantages in detecting low-concentration NO2 at near room temperature.
Here, we report time-resolved broadband transient reflectivity measurements performed in a single crystal of SnS 2 . We made use of time-domain Brillouin scattering and a broadband probe to measure the out-of-plane longitudinal sound velocity, [Formula: see text], in this semiconducting two-dimensional metal dichalcogenide. Our study illustrates the potential of this non-invasive all-optical pump–probe technique for the study of the elastic properties of transparent brittle materials and provides the value of the elastic constant [Formula: see text].
Layered two-dimensional (2D) tin dichalcogenides (SnS2 and SnSe2) have attracted considerable attention owing to their environmental friendliness, semiconducting character, and outstanding electrical and optoelectronic properties. The electronic properties of 2D tin dichalcogenides can be effectively tuned by substitutional doping to improve their performance and extend their applications. Here, we review the recent advances in metal and non-metal substitutional doping of tin dichalcogenides and the effect of doping on electrical, optoelectronic, and thermoelectric applications. Moreover, the challenges and outlook of substitutional doping of tin dichalcogenides are also discussed.
Dye-sensitized solar cells (DSSCs) are promising for indoor battery-less applications thanks to their high performance in office light conditions. The rare and expensive Pt metal is conventionally used as a high-performance counter electrode (CE) material in DSSCs. Carbon-based material is expected to be an economical alternative to Pt. The stability of the carbon-based CE in DSSCs working in indoor conditions has not been widely evaluated. In this study, a commercially available waterproof India ink was coated on a flexible activated carbon sheet to make the CE of a quasi-solid DSSC. The fabricated CE was flexible and low cost and could produce comparable conversion efficiency to a control Pt-coated glass CE under AM1.5G illumination. Moreover, the operation stability of the fabricated CE was evaluated for 1200 h under 250 lx indoor light intensity. The stable maximum power output of 5.4 μW/cm2 was obtained during the test period. In indoor light conditions, the DSSC using the fabricated CE showed higher output power density than that of the DSSC with the control Pt-coated glass CE.
Herein, we report the structural, morphological, optical and electrical properties of undoped and Ti-doped SnS2 thin films deposited on glass substrate by sol–gel spin coating technique. Grazing-Incidence X-ray diffraction and Raman analyses confirm the formation of hexagonal phase of as-deposited films. The structural parameters were estimated through GI-XRD data and found to be varying with Ti⁴⁺ concentration. Field effect scanning electron microscopy images show as-grown spherical nanoparticles with uniform deposition on the entire glass substrate. The UV–Vis absorption spectra were recorded to explore the optical properties of films. The analysis of data revealed the semiconductor nature of as-deposited films with a band gap of 2.24 eV in case of undoped SnS2. An intermediate band was also observed at 5 and 20 mol% Ti⁴⁺ concentration which directly indicates the extension of light absorption ability from visible to near infrared region of the solar spectrum. The X-ray photoelectron spectroscopy analysis was performed to confirm the existence of constituent elements in the as-deposited films with their oxidation state. The electrical properties were explored by I–V and Hall Effect measurements.
In this paper, Co-based metal organic framework mixtures (MOFs) stuff are used as self-sustain templates to prepare CoNi alloys and N-codop porous carbon composites ([email protected]) by one-step calcination and ion exchange methods and apply to the study of the counter electrode (CE) of dye-sensitized solar cells (DSSCs). [email protected] retains a large specific surface area, high porosity and abundant unsaturated sites of MOFs, and the conductivity and catalytic activity of porous carbon are improved by the introduction of CoNi alloy and N. At the same time, the nitrogen-doped porous carbon protects the CoNi alloy from corrosion of the electrolyte and ensures the stability of the material. [email protected] is used in DSSCs for catalytic reduction of I3⁻ exhibits the photoelectric conversion efficiency of 8.85%, that is overtop the exhibited by Pt CE under the equal conditions. Therefore, [email protected] composites are prepared based on MOFs are expected to instead of Pt as DSSCs CE materials because of their excellent optoelectronic properties and inexpensive.
After the discovery of graphene, there have been tremendous efforts in exploring various layered two-dimensional (2D) materials for their potential applications in electronics, optoelectronics, as well as energy conversion and storage. One of such 2D materials, SnS2, which is earth abundant, low in toxicity, and cost effective, has been reported to show a high on/off current ratio, fast photodetection, and high optical absorption, thus making this material promising for device applications. Further, a few recent theoretical reports predict high electrical conductivity and Seebeck coefficient in its bulk counterparts. However, the thermal properties of SnS2 have not yet been properly explored, which are important to materialize many of its potential applications. Here, we report the thermal properties of SnS2 measured using the optothermal method and supported by density functional theory (DFT) calculations. Our experiments suggest very low in-plane lattice thermal conductivity (κ=3.20±0.57Wm–1K–1) and cross-plane interfacial thermal conductance per unit area (g=0.53±0.09MWm–2K–1) for monolayer SnS2 supported on a SiO2/Si substrate. The thermal properties show a dependence on the thickness of the SnS2 flake. Based on the findings of our DFT calculations, the very low value of the lattice thermal conductivity can be attributed to low group velocity, a shorter lifetime of the phonons, and strong anharmonicity in the crystal. Materials with low thermal conductivity are important for thermoelectric applications as the thermoelectric power coefficient goes inversely with the thermal conductivity.
The influence of lyophilization on the electrochemical properties of hydrothermally synthesized tin (Sn) doped molybdenum sulfide (MoS2) nanostructures are investigated thoroughly. The lyophilized tin doped MoS2 used as counter electrode (CE) in dye-sensitized solar cells (DSSCs) showed high efficiency and better stability. Power conversion efficiency (PCE) of 7.14% is achieved using lyophilized 2.5% Sn-doped MoS2 as CE in DSSCs, which is much higher than devices made of CE comprising oven air annealed samples (5.74%). The major enhancement of PCE is due to the large surface area of Sn-doped lyophilized MoS2 nanostructures as well as the high electrocatalytic activity of MoS2 towards reduction reaction, which are observed from BET, CV and EIS measurements. Sequential CV scanning further showed the high electrochemical stability of the Sn-doped MoS2 nanostructures. This indicates the useful application of lyophilizer technique to produce various other metal sulfide nanostructures to increase the porosity and overall surface area of the materials for optimum device performance.
Synthesis of non-precious metal materials with cost-effective and excellent electrocatalytic activity as counter electrode (CE) of dye-sensitized solar cells (DSSCs) remains a challenge. Herein, MOF-based self-sustaining template and ion exchange method are developed to fabricate Co9S8 and Ni9S8 loaded on N-doped porous carbon nanocage materials (Co9S8/Ni9S8@C-N) with large specific surface area and remarkable catalytic activities to the reduction of I3⁻ ions. The excellent performance of Co9S8/Ni9S8@C-N is owing to the synergistic effect of Ni9S8 and Co9S8 can further improve the catalytic activity and N-doped porous carbon nanocage as a good conductor provides a suitable place for the redox reaction and guarantees the stability of the material. As a CE catalytic material, Co9S8/Ni9S8@C-N reveals excellent catalytic activity and stability, making the photoelectric conversion efficiency (PCE) 17.54% higher than Pt CE. The Co9S8/Ni9S8@C-N composite material reveals the remarkable potential as a CE in the DSSCs.
In the present study, synthesis of Zn²⁺ doped SnS2 (Sn1−xZnxS2) nanoparticles has been carried out using a novel thermal decomposition method. The characterization of Zn²⁺ doped SnS2 nanoparticles was done using various analytical techniques. XRD results indicate the formation of single phase up to x ≤ 0.5 and phase separation occurs when x ≥ 0.60. The morphology of SnS2 changes from flakes to flowers upon incorporation of Zn²⁺ as observed using scanning electron microscopy and transmission electron microscopy studies. The optical properties of Zn²⁺ doped SnS2 nanoparticles were studied by diffuse reflectance spectroscopy and the band gap of Zn²⁺ doped SnS2 nanoparticles can be varied from 2.24 eV to 2.48 eV. The Zn²⁺ doped SnS2 nanoparticles were explored as adsorbent for the removal of rhodamine B (RhB) from aqueous solutions.
In the present work, we have synthesized pure SnS, Fe-doped SnS, and Mn-doped SnS by the wet chemical precipitation technique. The grown samples were characterized structurally by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM). The purity of the samples was confirmed by the EDAX study. The doping changes the crystal size of the SnS NPs. The highest particle size of ~ 6.80 nm was observed for Mn-doped SnS and is confirmed by the TEM micro-graph. Optical properties were studied by UV–VIS absorption spectroscopy, photoluminescence (PL), and time-correlated single-photon counting (TCSPC) measurements. Among three samples, Mn-doped SnS shows the lowest bandgap energy of 2.00 eV. Natural dye-sensitized solar cells based on pure SnS as well as doped SnS NPs have been fabricated. Acalypha wilkesiana leaf extract was used as a natural dye which acts as photosensitizers. Our main target is to fabricate low cost but efficient solar cells with natural dye. The fabricated solar cells were characterized through the J-V study under the illumination of 100 mW/cm2. Open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), as well as power conversion efficiency (η) were also studied.
Severe bacterial infections have brought an urgent threat to our daily life, and photothermal therapy (PTT) has acted as an effective method to kill bacteria. Herein we decorated Ag on the surface of SnS2 (Ag@SnS2), which has outstanding photothermal conversion capability and good biocompatibility. The decoration of Ag on SnS2 improved the absorption of near-infrared (NIR) light in comparison to SnS2, resulting in a temperature increase of 50 °C after 5 min of NIR light irradiation (1.9 W cm-2) and a photothermal conversion efficiency of 31.3%. Ag@SnS2 exhibits almost 100% growth inhibition of E. coli and S. aureus bacteria due to hyperthermia, with a concentration larger than 0.5 mg mL-1 and 5 min of NIR irradiation. Meanwhile, SEM images of treated bacterial cells showed the attachment of Ag@SnS2 on the cell surface and obvious cellular membrane destruction. Ag@SnS2 can also accelerate in vivo wound healing through PTT-induced bacterial disinfection. Therefore, Ag@SnS2 exhibits great potential for photothermal antibacterial application and wound disinfection.
Tin disulfide can be a good electrode material in supercapacitors due to the presence of significant inter- layer space in crystalline structures and large surface area. However, there are only a few reports of its supercapacitor applications. In this study, we report flower-like pure SnS 2 and alkali metals (Li, Na, K and Cs) doped-SnS 2 nanostructures synthetized by simple single-step solvothermal method without use of any surfactants. Results show that due to the presence of dopants, with increasing radius of the dopant element, the interlayer distance and dislocation intensity increase. This leads to an increase in the ex- panded space between interlayer and electro-active sites, and therefore, it is possible to intercalate more ions from the electrolyte. But due to the higher conductivity of Na than the other alkali metals, Na doped- SnS 2 shows higher current density at constant voltage and thus better capacitance performance than the others. Na doped-SnS 2 exhibits higher supercapacitor performance with a high capacitance of 269 Fg −1 at a current density of 1 Ag −1 . The significant electrochemical performance of Na doped-SnS 2 can be attributed to its particularly good surface area due to the expansion of interlayer space, increasing of electro-active sites and greater conductivity due to the presence of Na.
Tin disulfide can be a good electrode material in supercapacitors due to the presence of significant interlayer space in crystalline structures and large surface area. However, there are only a few reports of its supercapacitor applications. In this study, we report flower-like pure SnS2 and alkali metals (Li, Na, K and Cs) doped-SnS2 nanostructures synthetized by simple single-step solvothermal method without use of any surfactants. Results show that due to the presence of dopants, with increasing radius of the dopant element, the interlayer distance and dislocation intensity increase. This leads to an increase in the expanded space between interlayer and electro-active sites, and therefore, it is possible to intercalate more ions from the electrolyte. But due to the higher conductivity of Na than the other alkali metals, Na doped-SnS2 shows higher current density at constant voltage and thus better capacitance performance than the others. Na doped-SnS2 exhibits higher supercapacitor performance with a high capacitance of 269 Fg⁻¹ at a current density of 1 Ag⁻¹. The significant electrochemical performance of Na doped-SnS2 can be attributed to its particularly good surface area due to the expansion of interlayer space, increasing of electro-active sites and greater conductivity due to the presence of Na.
Two dimensional (2D) microstructure materials have attracted considerable attention due to their short-diffusion path length and large interfacial areas for hybrid supercapacitors (HSCs) in recent years. In the typical layered metal chalcogenides family, tin sulfide (SnS 2) is one of the important binary compounds explored for energy storage applications. A reasonable construction of a 2D microstructure for HSCs is proposed. The structural study revealed the nanorods-like morphology with high purity and crystallinity of the sample. The 2D SnS 2 nanorods were synthesized through a controlled strategy and tested as an active electrode material for HSCs. The elec-trochemical properties of SnS 2 nanorods were examined through different experimental measurements, including both two-and three-electrode systems. In a three-electrode system, the as-synthesized 2D SnS 2 nanorods exhibit superior electrochemical properties with a specific capacitance of (270 F g − 1 at 10 mVs − 1 , and 162.2 F g − 1 at 3 A g − 1) and excellent cycling stability (9% capacitance loss after 8000 repeated CV cycles), due to efficient ion transport between the electrolyte to the active electrode, and charge transport between electrode and current collector, respectively. More importantly, aqueous HSCs were assembled using 2D SnS 2 //rGO as positive and negative electrodes operating in a wide and stable potential window up to 1.6 V in 1 M NaOH electrolyte. Moreover, HSCs deliver a high specific capacitance of (108 F g − 1 at 5 mVs − 1 , and 92.4 F g − 1 at 1 A g − 1), a high specific energy of 32.8 Wh kg − 1 along with excellent electrochemical stability (93% retention after 4000 cycles) due to the morphology assisted activity and unique structure of the electrode material. Additionally, we demonstrated the single HSC cell which provided sufficient energy to turn on a red LED of 20 mW and emit light over a certain period of time opens up possible realistic applications. The results manifest that the proposed hydrothermal assisted synthesis has promising applications in producing high-performance energy storage devices.
Sensing of Nitrogen dioxide (NO2) is of great importance for its pernicious and destructive impacts to both human health and nature environment. However, it still remains challenging to achieve the NO2 detection with fast response, high sensitivity and good selectivity. In this work, two-dimensional (2D) ultrathin n-type SnS2 nanosheets with Mo doping have been synthesized via a simple single-step solvothermal method and exploited for NO2 sensing application. Phase and structural analyses confirm the homogeneous cation alloying of Mo (1% ∼ 10%) in the SnS2. It is indicated that the Mo doping can elegantly tune the electronic structure of SnS2 and promote the sensing process with negative adsorption energy. Especially for 3%Mo-SnS2 nanosheet, the NO2 sensing response at 150 ℃ has been enhanced around 23 times relative to the un-doped SnS2 sample, together with fast sensing kinetics and good NO2 selectivity. Interestingly, the n-type SnS2-based sensor shows an abnormal response characteristic for the first time with resistance decrease at low NO2 concentration, behaving like a p-type semiconductor. The P-N sensing transition can be regulated by varying the operation temperature and NO2 concentration. Mechanisms for the enhanced sensing and abnormal phenomena are well explained based on density function theory calculations. Such P-N sensing switch in a single sensor here opens up interesting possibilities for the highly sensitive and selective detection of NO2 with 2D metal dichalcogenides.
A novel Ag-doped SnS2@InVO4 composite was successfully synthesized for efficient uranium removal from wastewater through a facile hydrothermal method. The structure, morphology and optical property of materials were characterized using various instruments. The results proved that Ag-doped SnS2@InVO4 composite presented as hexangular nanosheets with about 4.87 nm pore size and 101.58 m²/g specific surface area. Further characterization demonstrated that photo-adsorption ability of visible light was enhanced and band gap was narrowed. The adsorption kinetics and isotherm of U(VI) on Ag-doped SnS2@InVO4 composite could be depicted via the Langmuir model and pseudo-second-order mode, and the maximum adsorption capacity of U(VI) reached 167.79 mg/g. The elimination of U(VI) of as-synthesized composites was studied by a synergy of adsorption and visible-light photocatalysis, and the optimal content of InVO4 was found to be 2 wt% with the highest removal efficiency of 97.6%. In addition, compared with pure SnS2 and Ag-doped SnS2, the Ag-doped SnS2@InVO4 composites exhibited superior photocatalytic performance for the conversion of soluble U(VI) to insoluble U(IV) under visible light. The excellent photocatalytic performance was mainly attributed to numerous surface-active sites, strong optical adsorption ability and narrow band gap. Simultaneously, the heterojunction between Ag-doped SnS2 and InVO4 promoted the separation and transfer of photoexcited charges. The cyclic experiments indicated the Ag-doped SnS2@InVO4 composite remained good structural stability and reusability. Finally, the possible mechanism was discussed based on the experimental analysis.
In this study, we highlight that surface nitrogen-injection engineering brings high formation rate for CO2 reduction to formate, which is high level among the reported electrocatalysts. Surface nitrogen-injection engineering can increase the amounts of active sites and optimize the electronic structure simultaneously. Taking an example of SnS2 precursors, the final-obtained surface N enriched Sn(S) nanosheets (denoted as N-Sn(S) nanosheets) exhibit a 5-fold of current density and 2.45-fold of Faradaic efficiency than pristine SnS2 derived Sn(S) nanosheets (denoted as Sn(S) nanosheets). On account of high activity and selectivity, the formation rate of formate is 14 times than pristine samples and reaches up to 1358 μmol h-1 cm-2. Moreover, this strategy is proved to be general to other metal sulfide, such as CuS and In2S3. We anticipate that surface nitrogen-injection engineering offers new avenues to rational design of advanced electrocatalysts for CO2 reduction reaction.
Tin disulfide has attracted much attention on solar cell study due to its excellent optoelectronic properties in addition to just containing low-cost and non-toxic elements. Based on the HSE06-hybrid function calculations combined with Grimme's dispersion-correction method, a half-filled and delocalized intermediate band(IB) is presented in the main band gap of SnS2 after partially Sb substituting on Sn site, which is made of the antibonding states of Sb-s and S-p states. Three-photon absorption can be realized in the doped sample and its corresponding absorption coefficient is enhanced at the visible light region thanks to the isolated and half-filled IB above the original valence band. Furthermore, SbSn always has the lowest formation energy than other Sb-related defects (i.e. SbS and Si) based on the defect formation energy calculations. Therefore, Sb-doped SnS2 is suggested as a promising candidate for the absorber of intermediate band solar cell.
A reasonable formation of an electrode material with three‐dimensional (3D) microstructure for supercapacitors was proposed. Two‐dimensional (2D) SnS2 nanoplates were uniformly in situ grown on 3D carbon foam (CF) through a controllable strategy. The composite displayed excellent electrochemical performance due to the synergistic effect of SnS2 and CF. The SnS2@CF‐2 composite containing 23.92 wt% of SnS2 has a superior specific capacitance of 283.6 F g−1 at the current density of 1 A g−1. Moreover, a symmetric supercapacitor based on SnS2@CF‐2 composite has a capacitance of 82.5 F g−1 at 1 A g−1 and a high energy density of 13.9 Wh kg−1 at the power density of 551.7 W kg−1. This research article entitled “A Free‐Standing Electrode Based on 2D SnS2 Nanoplates@3D Carbon Foam for High Performance Supercapacitors” completed by Dongfeng Wang, Xuehua Yan*, Chen Zhou, Jingjing Wang, Xiaoxue Yuan, Hui Jiang, Yihan Zhu, Xiaonong Cheng and Ruifeng Li. No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co‐authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed. SnS2 nanoplates were synthesized uniformly on free‐standing carbon foam network. SnS2@CF composite shows 283.7 F g−1 at a current density of 1 A g−1. Assembled coin cell supercapacitor delivered a high energy density of 13.9 Wh kg−1.
Exploitation of highly efficient catalysts for photocatalytic degradation of volatile organic compounds (VOCs) under visible light irradiation is highly desirable yet challenging. Herein, well-aligned 2D Ni-MOF nanosheet arrays vertically grown on porous nickel foam (Ni-MOF/NF) without lateral stacking was successfully prepared via a facile in-suit solvothermal strategy. In this process, Ni foam could serve as both skeletons to vertically support the Ni-MOF nanosheets and self-sacrificial templates to afford Ni ions for MOF growth. The Ni-MOF/NF nanosheet arrays with highly exposed active sites and light harvesting centres as well as fast mass and e‒ transport channels exhibited excellent photocatalytic oxidation activity and mineralization efficiency to typical VOCs emitted form paint spray industry, which was almost impossible for its three-dimensional (3D) bulk Ni-MOF counterparts. A mineralization efficiency of 86.6% could be achieved at 98.1% of ethyl acetate removal. The related degradation mechanism and possible reaction pathways were also attempted based on the electron paramagnetic resonance (EPR) and online Time-of-Flight Mass Spectrometer (PTR-ToF-MS) results.
Transition metal sulfides are generally subject to unsatisfactory capacity and rate capability that still restrict their application for sodium-ion batteries. Herein, the yolk-shell P-doped NiS2/C spheres via Ni-MOFs template are synthesized with phytic acid acting as P source to significantly enhance the sodium storage property. The yolk-shell P-doped NiS2/C can exhibit ultrahigh initial discharge and charge capacities (3546.7/2622.9 mAh g−1 with 72.9% Coulombic efficiency), excellent reversible capacity of 1113.5 mAh g−1 at 0.1 A g−1 with outstanding rate capability, and stable long cycle performance of 766.8 mAh g−1 at 0.5 A g−1 after 400 cycles. The satisfactory electrochemical results can be ascribed to the confinement and synergistic effect from stable yolk-shell framework and heteroatom P doping. Therefore, morphology tuning and heteroatom P doping can be served as effective strategies to significantly improve electrochemical properties of transition metal sulfides for sodium-ion batteries
Element doping is an effective strategy to enhance the selectivity of electrochemical carbon dioxide reduction. In this work, a dendritic core-shell In-doped [email protected]2O catalyst is prepared by co-electrodeposition method on carbon fiber paper for selective electroreduction of CO2 to CO. Faradaic efficiency of producing CO over this dendritic In-doped [email protected]2O reaches 87.6 ± 2.2% with total current density of 11.1 ± 0.85 mA cm⁻² at −0.8 V vs RHE, which outperforms most of the reported Cu-based electrocatalysts. The excellent performance is mainly derived from charge re-distribution and the enhanced intrinsic activity due to the formation of In-doped Cu2O layer. Meanwhile, the Cu⁺/Cu⁰ can be adjusted by tailoring the doped-In content. The relatively high ECSA and small charge transfer resistance are also conducive to improve the selectivity and activity. The oxyphilic In metal incorporated into the copper lattice can well stabilize the intermediate *COOH through enhancing interaction with O-ends of *COOH. This work provides a facile approach and a deep insight on design and synthesis of high efficiency hybrid electrocatalysts.
Layered SnS2 are considered as a promising anode candidate for sodium-ion batteries yet suffering from low initial Coulombic Efficiency, limited specific capacity and rate capability. Herein, we report a cobalt metal cation doping strategy to enhance the electrochemical performance of SnS2 nanosheet array anode through a facile hydrothermal method. Benefitting from this special structure and heteroatom-doping effect, this anode material displays a high initial Coulombic Efficiency of 57.4%, superior discharge specific capacity as high as 1288 mAh g-1 at 0.2 A g-1 after 100 cycles and outstanding long-term cycling stability with a reversible capacity of 800.4 mAh g-1 even at 2 A g-1. These excellent performances could be ascribed to the Co-doping effect that can increase the interlayer spacing and produce rich defects, regulate the electronic environment and improve conductivity. Besides, carbon cloth substrate can maintain the integrity of electrode material framework and buffer their volume variation, thus boosting intrinsic dynamic property and enhancing sodium storage performance.
The spinel Li4Mn5O12 has been considered as a prospective 3 V cathode material for the next generation of lithium-ion batteries (LIBs) due to its high energy density and excellent cycling stability. However, the low operating voltage (∼3 V) makes Li4Mn5O12 impractical for high-energy high-power LIBs. To address this issue, Ni and Fe dual doped Li4Mn5-x-yNixFeyO12 has been prepared via a facile sol-gelmethod combined with post-heat-treatment. The effects of dual-cations doping on the crystal structure,morphology and electrochemical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and galvanostatic charge/discharge analysis. As a result, Li4Mn4Ni0.5Fe0.5O12 exhibits the highest reversible specific capacity of 133 mAh/g at a specific current density of 25 mA/g after 100 cycles and exhibits a significantly improved high voltage performance with corresponding capacity of ∼80 mAh/g at an average voltage of 4.7 V vs. Li/Li+ and ∼122 mAh/g at above 4.0 V. These results indicate the dual doping of Ni and Fe can effectively improve both the operating voltage and reversible specific capacity of Li4Mn5O12 with excellent cycling stability, demonstrating a promising high-voltage cathode material for high-energy high-power LIBs.
Tin sulfide is being widely investigated as an earth-abundant light harvesting material, but recorded efficiencies for SnS fall far below theoretical limits. We describe the synthesis and characterization of the single-crystal tin sulfides (SnS, SnS2, and Sn2S3) through chemical vapor transport, and combine electronic structure calculations with time-resolved microwave conductivity measurements to shed light on the underlying electrical properties of each material. We show that the coexistence of the Sn(II) and Sn(IV) oxidation states would limit the performance of SnS in photovoltaic devices due to the valence band alignment of the respective phases and the “asymmetry” in the underlying point defect behavior. Furthermore, our results suggest that Sn2S3, in addition to SnS, is a candidate material for low-cost thin-film solar cells.
Pt-like electrocatalytic activity of MoN, WN, and Fe2N for dye-sensitized solar cells (DSSCs) is demonstrated in this work. Among the transition metal nitrides, MoN has superior electrocatalytic activity and a higher photovoltaic performance. This work presents a new approach for developing low-cost and highly-efficient counter electrodes for DSSCs.
An inexpensive microporous polyaniline (PANI) is used as a substitute for platinum to construct the counter electrode in dye-sensitized solar cells (DSSCs). The PANI counter electrode with microporosity and a size diameter of about 100nm possesses lower charge-transfer resistance and higher electrocatalytic activity for the I3-/I- redox reaction than Pt electrode does. The overall energy conversion efficiency of the DSSC with PANI counter electrode reaches 7.15%, which is higher than that of the DSSC with Pt counter electrode. The excellent photoelectric properties, simple preparation procedure and inexpensive cost allow PANI electrode to be a credible alternative for DSSCs.
Wurtzite CuInS2–ZnS heterostructured nanorods are synthesized via a seed-assisted synthetic route. Cu1.94S–ZnS heterostructured nanorods are transformed into CuInS2–ZnS by reacting with indium ions to convert copper sulfide to wurtzite CuInS2. The shapes of the CuInS2–ZnS heterostructured nanorods can be tuned from burning torch-like to longer rod-like by varying the concentration of added indium. Dye-sensitized solar cells (DSSCs) using these heterostructured nanocrystals as counter electrodes had a power conversion efficiency (7.5%) superior to DSSCs made with conventional platinum electrode (7.1%) under the same device configuration.
Solar cells based on dye-sensitized mesoporous films of TiO2 arelow-cost alternatives to conventional solid-state devices. Impressive solar-to-electrical energy conversion efficiencies have been achieved with such films when used in conjunction with liquid electrolytes. Practical advantages may be gained by the replacement of the liquid electrolyte with a solid charge-transport material. Inorganic p-type semiconductors, and organic materials have been tested in this regard, but in all cases the incident monochromatic photon-to-electron conversion efficiency remained low. Here we describe a dye-sensitized heterojunction of TiO2 with the amorphous organic hole-transport material 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9'-spirobifluorene (OMeTAD; refs. 10 and 11). Photoinduced charge-carrier generation at the heterojunction is very efficient. A solar cell based on OMeTAD converts photons to electric current with a high yield of 33%.
A hierarchical SnO2@SnS2 core-shell nanostructure has been prepared by in situ surface sulfurization of hollow SnO2 sphere via a facile two-step solution-based method and used as a substitute for conventional Pt counter electrode (CE) for dye-sensitized solar cells (DSSCs) for the first time. The resulted semitransparent SnO2@SnS2 CEs demonstrate a high electrical conductivity and excellent catalytic activity, which are attributed to the synergetic effect of each component in such hierarchical nanostructure. The hierarchical SnO2@SnS2 CE achieves an impressive photovoltaic conversion efficiency (PCE) of 8.08%, which is significantly higher than those of individual SnO2 (5.26%) and SnS2 (6.00%) and also higher than Pt (7.88%) by 2.5%. This study suggests that the inexpensive hierarchical SnO2@SnS2 CE is a good alternative to the expensive Pt CE in DSSCs.
Complex hierarchical structures have received tremendous attention due to their superior properties over their constitute components. In this study, hierarchical graphene-encapsulated hollow SnO2@SnS2 nanostructures are successfully prepared by in-situ sulfuration on the backbones of hollow SnO2 spheres via a simple hydrothermal method followed by a solvothermal surface modification. The as-prepared hierarchical SnO2@SnS2@rGO nanocomposite can be used as anode material in lithium ion batteries, exhibiting excellent cycleability with a capacity of 583 mAh/g after 100 electrochemical cycles at a specific current of 200 mA/g. This material shows a very low capacity fading of only 0.273% per cycle from the 2nd to the 100th cycle, lower than the capacity degradation of bare SnO2 hollow spheres (0.830%) and single SnS2 nanosheets (0.393%). Even after being cycled at a range of specific current varied from 2000 mA/g to 100 mA/g, hierarchical SnO2@SnS2@rGO nanocomposite maintains a reversible capacity of 664 mAh/g, which is much higher than single SnS2 nanosheets (374 mAh/g) and bare SnO2 hollow spheres (177 mAh/g). Such significantly improved electrochemical performance can be attributed to the unique hierarchical hollow structure, which not only effectively alleviates the stress resulted from the lithiation/delithiation process and maintains structural stability during cycling but also reduces aggregation and facilitates ion transportation. This work thus demonstrates the great potential of hierarchical SnO2@SnS2@rGO nanocomposites for application as high-performance anode material in next-generation lithium ion battery technology.
The dye-sensitized solar cell (DSSC) plays a leading role in third generation photovoltaic devices. Platinum-loaded conducting glass has been widely exploited as the standard counter electrode (CE) for DSSCs. However, the high cost and the rarity of platinum limits its practical application in DSSCs. This has promoted large interest in exploring Pt-free CEs for DSSCs. Very recently, graphene, which is an atomic planar sheet of hexagonally arrayed sp2 carbon atoms, has been demonstrated to be a promising CE material for DSSCs due to its excellent conductivity and high electrocatalytic activity. This article provides a mini review of graphene-based CEs for DSSCs. Firstly, the fabrication and performance of graphene film CE in DSSCs are discussed. Secondly, DSSC counter electrodes made from graphene-based composite materials are evaluated. Finally, a brief outlook is provided on the future development of graphene-based materials as prospective counter electrodes for DSSCs.
NiO is an important heterogeneous catalyst employed in chemical processes. However, it is a new topic to explore NiO as a counter electrode catalyst for dye-sensitized solar cells (DSSCs). In this paper, NiO with poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) was demonstrated an efficient DSSC counter electrode with a maximum power conversion efficiency of 7.58 %. Furthermore, electrochemical impedance spectroscopy and cyclic voltammetry measurements revealed that the excellent photovoltaic performance is due to the combination between the high catalytic activity of NiO and the superior electrical conductivity of PEDOT:PSS. The optimum weight ratio of NiO to PEDOT:PSS is 48.
In the present work, we use chemical exfoliation to fabricate ultrathin two-dimensional anatase TiO2 nanosheets (NSs) for application as photoanode materials in dye-sensitized solar cells. For the first time, colloidal Ti0.91O2 NSs are synthesized via chemical exfoliation of a layered precursor (HxTi2-x/4 square O-x/4(4)center dot H2O; square: vacancy, x = 0.7) through ion exchange with tetrabutylammonium (TBA(+)) cations. The as-prepared Ti0.91O2 NSs are well-dispersed and ultrathin with a lateral size of up to a few micrometers. Subsequent acid treatment induces colloidal Ti0.91O2 to reassemble and precipitate into a gelation form, followed by thermal annealing to convert the Ti0.91O2 gelation into anatase TiO2 nanosheets for applications as photoanode materials in DSSCs. Because of the enhanced light absorption and dye absorption resulting from the high surface area of ultrathin TiO2 nanosheets, the DSSC consisting of 8.8 mu m thick TiO2 nanosheet film delivers the highest energy conversion efficiency of 4.76% and the largest short-circuit current of 9.30 mA cm(-2), among DSSCs based on TiO2 nanosheet films of various thicknesses. It is noted that an overly thick TiO2 NS film will not further increase DSSC efficiency because the thicker layer results in a longer pathway for electron transport and more electron hole recombination. Moreover, a ZrO2 ALD coating combined with TiCl4 treatment on TiO2 NS film can effectively enhance the efficiency of DSSCs to 7.33% by significantly creating more surface area for more dye loading and preventing electron hole recombination between TiO2 and the dye/electrolyte, respectively.
In this paper, we focused on synthesizing hexagonal SnS2 nanoparticles with perfect crystallinity as a replacement of Pt catalyst conventionally used in the counter electrode (CE) of a dye-sensitized solar cell (DSSC). When the conditions of the initial reaction were changed, the SnS2 nanoparticles growth along the (001) facet with various preferred orientations was obtained. The highest power conversion efficiency (PCE) of our materials achieved 6.3%, while the efficiency of Pt based was 6.67%. From the electrochemical impedance spectroscopy analysis, we found that our dye-sensitized solar cell offers lower interface resistance between the electrolyte and the counter electrode. Our work obtained the DSSC with the power-conversion efficiency and stable property, and it also provided routes for preparing low-cost DSSC using inorganic nanostructure as CE.
In this study, porous SnO2 nanosheets composed of SnO2 nanoparticles were prepared by calcining SnS2 nanosheets. The SnO2 nanoparticles have an average diameter of 15-20 nm and porous SnO2 nanosheets have a large specific surface area of 37.39 m(2)/g. As photoanodes, the dye-sensitized solar cell (DSSCs) based on porous SnO2 nanosheets show a superior power conversion efficiency of 0.562%, improved by 134.2% compared to pure SnO2 nanoplate (0.240%). The efficiency improvement could be attributed to the unique porous architecture, which provides efficient electron channels and excellent ability of light scattering.
A nanocomposite of SnS2 nanoparticles with reduced graphene oxide (SnS2@RGO) had been successfully synthesized as a substitute conventional Pt counter electrode (CE) in dye-sensitized solar cell (DSSC) system. The SnS2 nanoparticles were uniformly dispersed onto graphene sheets, which formed a nano-sized composite system. The effectiveness of this nanocomposite exhibited remarkable electro-catalytic property on reducing the triiodide, owning to synergetic effect of SnS2 nanoparticles dispersed on graphene sheet and the improved conductivity. Consequently, the DSSC equipped with SnS2@RGO nanocomposite CE achieved a power conversion efficiency (PCE) of 7.12%, which was higher than those of use SnS2 nanoparticles (5.58%) or graphene sheet alone (3.73%) as CEs, and also comparable to 6.79% obtained with pure Pt CE for a reference.
A low-cost, sulfur-doped NiO (S–NiO) thin film is electrodeposited on fluorine-doped SnO2 substrate and studied in an iodide-based redox system. High electrochemical activity is present because of a large catalytic surface area and a low charge transfer resistance. A dye- sensitized solar cell with a low-loaded S–NiO counter electrode achieves a power conversion efficiency of 5.04%, close to that of a cell with a conventional platinized electrode.
The various phases of tin sulfide have been studied as semiconductors since the 1960s and are now being investigated as potential earth-abundant photovoltaic and photocatalytic materials. Of particular note is the recent isolation of zincblende SnS in particles and thin-films. Herein, first-principles calculations are employed to better understand this novel geometry and its place within the tin sulfide multiphasic system. We report the enthalpies of formation for the known phases of SnS, SnS2, and Sn2S3, with good agreement between theory and experiment for the ground-state structures of each. While theoretical X-ray diffraction patterns do agree with the assignment of the zincblende phase demonstrated in the literature, the structure is not stable close to the lattice parameters observed experimentally, exhibiting an unfeasibly large pressure and a formation enthalpy much higher than any other phase. Ab initio molecular dynamics simulations reveal spontaneous degradation to an amorphous phase much lower in energy, as Sn(II) is inherently unstable in a regular tetrahedral environment. We conclude that the known rocksalt phase of SnS has been mis-assigned as zincblende in the recent literature.
A new type of semitransparent SnS2 nanosheet (NS) films were synthesized using a simple and environmentally friendly solution-processed approach, which were subsequently used as a counter electrode (CE) alternative to the noble metal Pt for triiodide reduction in dye-sensitized solar cells (DSSCs). The resultant SnS2 -based CE with a thickness of about 300 nm exhibited excellent electrochemical catalytic activity for catalyzing the reduction of triiodide and demonstrated comparable power conversion efficiency of 7.64 % with that of expensive Pt-based CE in DSSCs (7.71 %). When functionalized with a small amount of carbon nanoparticles, the SnS2 NS-based CE showed even better performance of 8.06 % than Pt under the same conditions. Considering the facile fabrication method, optical transparency, low cost, and remarkable catalytic property, this study on SnS2 NSs may shed light on the large-scale production of electrocatalytic electrode materials for low-cost photovoltaic devices.
Tin sulfide is being widely investigated as an earth-abundant light harvesting material, but recorded efficiencies for SnS fall far below theoretical limits. We describe the synthesis and characterization of the single-crystal tin sulfides (SnS, SnS2, and Sn2S3) through chemical vapor transport, and combine electronic structure calculations with time-resolved microwave conductivity measurements to shed light on the underlying electrical properties of each material. We show that the coexistence of the Sn(II) and Sn(IV) oxidation states would limit the performance of SnS in photovoltaic devices due to the valence band alignment of the respective phases and the "asymmetry" in the underlying point defect behavior. Furthermore, our results suggest that Sn2S3, in addition to SnS, is a candidate material for low-cost thin-film solar cells.
In the present work, pulse current deposition is used to deposit evenly distributed and uniformly sized Ag nanoparticles onto a TiO2 nanotube array as photoelectrode in dye-sensitized solar cells (DSSCs), and the size and amount of loading Ag nanoparticles are controlled by the pulse deposition time. Due to the enhanced light absorption and electron–hole separation caused by plasmon effect, DSSCs based on Ag-modified TiO2 nanotube arrays show higher energy conversion efficiencies than those based on bare nanotubes with the same tube length. Particularly, DSSC based on nanotubes modified using pulse deposition time 1 s/3 s delivers the highest energy conversion efficiency of 1.68% and the largest short-circuit current of 4.37 mA/cm2, while DSSC consisting of bare nanotubes exhibits efficiency of 1.20% and short-circuit current of 2.27 mA/cm2, which represents a 40% enhancement of cell efficiency in DSSC based on Ag-modified TiO2 nanotubes. It is also noted that overly long pulse deposition time will not further increase DSSC efficiency due to agglomeration of Ag particles. For example, when the pulse deposition time is increased to 2 s/6 s, DSSC based on Ag-modified nanotubes exhibits a lower efficiency of 1.42%. Moreover, high-concentration TiCl4 treatment on TiO2 nanotube arrays can further increase the energy conversion efficiencies to 3.82% and 2.61% for DSSC based on Ag-modified TiO2 nanotubes and DSSC based on bare TiO2 nanotubes, respectively, by significantly creating more surface area for dye loading.
Hexagonal phase SnS2 nanoflakes have been synthesized by reactions between an organotin precursor tetrabutyltin [TBT, (CH2CH2CH2CH3)4Sn] and carbon disulfide in hexanes at 180–200°C for 10-40 h. The structure, morphologies, composition, and properties have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), ICP-AES, and Raman and Mössbauer spectroscopies. XRD patterns determined the hexagonal SnS2 with lattice parameters a=3.6384 Å, c=5.9201 Å obtained in n-hexane, and a=3.6389 Å, c=5.9288 Å in cyclohexane. The flakelike morphologies were mainly caused by the anisotropic growth of SnS2. A possible mechanism is given in the paper.
Multi-walled carbon nanotubes (MWCNT) coated with a thin layer of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide were successfully fabricated by physical adsorption. They were then incorporated into poly(1-(2-acryloyloxy-ethyl)-3-methyl-imidazol-1-ium iodide (poly(AMImI))-based electrolytes to create an all-solid state dye-sensitized solar cell (DSSC). The power conversion efficiency (PCE) of the resulting DSSC was significantly increased, higher than that using poly(AMImI)-grafted MWCNT incorporated in the poly(AMImI)-based electrolytes. With gradual increases in the 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT content from 0 to 0.5 wt%, the PCE increased from 1.156 to 3.551% at full sun and the short-circuit current density (JSC) increased from 2.367 to 8.505 mA cm−2. According to the linear sweep voltammetry measurements, the presence of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT in the solid-state electrolytes significantly increased the limiting current and the diffusion coefficient of I3−. Notably, the relationship between the JSC and the increase of limiting current with the content of 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide-physisorbed MWCNT is linear.
In this study, cobalt sulfide (CoS) counter electrodes (CEs) fabricated by potentiodynamic deposition in a near-neutral solution (pH 6) were incorporated into Pt-free dye-sensitized solar cells (DSSCs). It was found that the potentiodynamic deposition mode can facilitate the formation of CoS within the deposit compared to the conventional chronoamperometric deposition. Different sweep cycle (charge capacity) had great impact on the morphology and electrocatalytic activity of CoS films. The CoS film fabricated by five-sweep-cycle potentiodynamic deposition was observed with highly porous morphology and multilayer structure, thus resulting in a lower charge-transfer resistance of ∼1.03Ωcm2 in comparison with a sputtered-Pt CE. The DSSC assembled with this kind of CoS CE showed a higher photovoltaic conversion efficiency of 6.33±0.15% compared to 6.06±0.17% for DSSC with the sputtered-Pt CE under full sunlight illumination (100mWcm−2, AM 1.5G). In addition, consecutive cyclic voltammetric and long-term light soaking tests demonstrated that such DSSC had excellent stability. Therefore, the highly porous CoS film can be considered as a promising alternative CE for use in DSSC due to its high electrocatalytic performance and electrochemical stability.
Polyvinylpyrrolidone (PVP)/Ag2S composite fibres were successfully prepared by a facile method called the electrospinning technique. Scanning electron microscopy analysis revealed the fibre morphology of the composite. Transmission electron microscopy showed spherical nanoparticles of the Ag2S component with an average particle size of about 15 nm and a good dispersion. X-ray diffraction results showed that a pure beta-Ag2S phase was obtained in the PVP fibres. X-ray photoelectron spectra (XPS) proved that the Ag and S elements exist in PVP/Ag2S composite fibres and quantitative analysis of the XPS showed that the atomic ratio of silver and sulfur was about 2. Fourier transform infrared and ultraviolet-visible spectroscopy were used to characterize the structure of the PVP/Ag2S composite fibres.
Using two identical hemispherical electron spectrometers with pre-retarding potential proportional to the energy analysed, precisely consistent values
Novel flowerlike SnS2 and In3+-doped SnS2 hierarchical structures have been successfully synthesized by a simple hydrothermal route using biomolecular l-cysteine-assisted methods. The l-cysteine plays an important role both as assistant and as sulfur source. Experiments with various parameters indicate that the pH values have a strong effect on the morphology of the assembly. Based on the experiments, a growth mechanical process was proposed. The synthetic samples were characterized by XRD, SEM, TEM (HRTEM), BET measurement, TGA, and XPS in detail. Further investigation of the photocatalytic degradation of three different dyes, methylene blue, methylene green, and ethyl violet, indicate that both samples have high photocatalytic activity, and the doped In3+ has enhanced the photoactivity of SnS2.
Glasses with the composition xLi2S(1-x)SiS2 [x ⩽ 0.6] have been prepared by twin roller quenching. Their glass transition temperatures and their electrical conductivities have been measured. The conductivity reaches a maximum value of 5.10−4 (Ω.cm)−1 at 25°C By dissolving a halide salt (LiI) in the matrix, this value has been improved to 8.2 10−4 (Ω.cm)−1 which is almost the highest conductivity obtained with Li conductive glasses.
Crystalline tin-sulfide nanosheets are synthesized through a one-step solvothermal process and incorporated in the negative electrode material for lithium-ion batteries. SnS2 compounds synthesized in ethylene glycol have an approximately 2nm-thick nanosheet morphology and exhibit an excellent charge-capacity retention of ∼95% after 50 cycles between 1.15 and 0V at 0.5C (=323mAg−1). The thickness of the nanosheets is varied up to ∼26nm by adjusting the precursors, solvents and source concentrations. The nanostructural effects are investigated in terms of electrochemical and rate-capability properties.
Graphene nanosheets (GNs) were synthesized and used as a substitute for platinum as counter-electrode materials for dye-sensitized solar cells (DSSCs). The as-synthesized GNs were dispersed in a mixture of terpineol and ethyl cellulose. GN films were screen-printed on fluorine-doped tin oxide (FTO) slides using the formed GN dispersions. GN counter-electrodes were produced by annealing the GN films at different temperatures. The annealed GN films revealed an unusual 3D network structure. Structural and electrochemical properties of the formed GN counter-electrodes were examined by field emission scanning electron microscopy, Raman spectroscopy and electrochemical impedance spectroscopy. It was found that the annealing temperature of GN materials played an important role in the quality of the GN counter-electrode and the photovoltaic performance of the resultant DSSC. The grown DSSCs with graphene-based counter-electrodes exhibited a conversion efficiency high up to 6.81%.
SnS nanosheets (NSs), SnS nanowires (NWs) and SnS2 nanosheets were synthesized and investigated as counter electrode (CE) catalysts in a I-3(-)/I- based dye- sensitized solar cell (DSC) system for the first time. It is found that the SnS NS based DSCs show comparable power- conversion efficiency (E-ff = 6.56%) to Pt (7.56%), while the E-ff of SnS NW and SnS2 NS based DSCs are 5.00% and 5.14% respectively, indicating the excellent catalytic activity of SnSx for the reduction of triiodide to iodide.
Due to the advantages of both rapid electron transport of graphitic carbon and high catalytic performance of Fe3C nanoparticle, highly crystalline graphitic carbon (GC) / Fe3C nanocomposites have been prepared by a facile solid-state pyrolysis approach and used as counter electrode materials for high-efficiency dye-sensitized solar cells (DSSCs). The content of Fe3C in the composites can be modified by different hydrochloric acid treatment time. In comparison with pure highly crystalline GC, the DSSC based on GC/Fe3C nanocomposite with 13.5 wt% Fe3C content shows higher conversion efficiency (6.04 %), which indicates a comparable performance to the Pt-based DSSC (6.4 %) as well. Moreover, not only does our DSSCs have comparable performance to that of the Pt-based DSSC (6.4 %), but also is more cost-effective as well. In order to evaluate the chemical catalysis and stability of nanocomposite counter electrodes toward I3- reduction and the interfacial charge transfer properties, GC/Fe3C nanocomposites have been quantitatively characterized by cyclic voltammetry, electrochemical impedance spectra, and Tafel polarization curve. All the results have revealed that the GC / Fe3C nanocomposite counter electrodes can exhibit high catalytic performance and fast interfacial electron transfer, which can be acted as a very promising and high cost-effective materital for DSSCs.
Advances in the fields of catalysis and electrochemical energy conversion often involve nanoparticles, which can have kinetics surprisingly different from the bulk material. Classical theories of chemical kinetics assume independent reactions in dilute solutions, whose rates are determined by mean concentrations. In condensed matter, strong interactions alter chemical activities and create variations that can dramatically affect the reaction rate. The extreme case is that of a reaction coupled to a phase transformation, whose kinetics must depend not only on the order parameter but also on its gradients at phase boundaries. Reaction-driven phase transformations are common in electrochemistry, when charge transfer is accompanied by ion intercalation or deposition in a solid phase. Examples abound in Li-ion, metal–air, and lead–acid batteries, as well as metal electrodeposition–dissolution. Despite complex thermodynamics, however, the standard kinetic model is the Butler–Volmer equation, based on a dilute solution approximation. The Marcus theory of charge transfer likewise considers isolated reactants and neglects elastic stress, configurational entropy, and other nonidealities in condensed phases.
A review of the available electrical and structural data on both pure and doped 1T-TaS2 leads us to propose that the nearly commensurate to commensurate transition at 200 K is accompanied by Mott localization in two dimensions. One electron out of 13 in the Ta plane is localized onto the centre of a star of 13 Ta atoms. The picture helps in understanding the concentration dependence of the low-temperature resistivity in cation-doped samples, particularly the sharp maximum at an atomic fraction x ∼ 0.08 for Ti doping. Examining recent resistivity data by Di Salvo and Graebner (1977) we find that at low temperatures the conduction mechanism assumes a three-dimensional character. The lack of a Curie-type susceptibility in spite of electron localization is ascribed to spin-orbit coupling, according to an earlier suggestion by Geertsma, Haas, Huisman and Jellinek (1972).
THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods1. Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm-2) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.
Until now, photovoltaics--the conversion of sunlight to electrical power--has been dominated by solid-state junction devices, often made of silicon. But this dominance is now being challenged by the emergence of a new generation of photovoltaic cells, based, for example, on nanocrystalline materials and conducting polymer films. These offer the prospect of cheap fabrication together with other attractive features, such as flexibility. The phenomenal recent progress in fabricating and characterizing nanocrystalline materials has opened up whole new vistas of opportunity. Contrary to expectation, some of the new devices have strikingly high conversion efficiencies, which compete with those of conventional devices. Here I look into the historical background, and present status and development prospects for this new generation of photoelectrochemical cells.
In this work, Fe-doped ZnO thin films were prepared by sol–gel method on Si and glass substrates and influence of Fe-doping concentration on the structural and optical properties of the films was studied. The X-ray diffraction (XRD) analyses show that all the ZnO thin films prepared in this work have a hexagonal wurtzite structure and are preferentially oriented along the c-axis perpendicular to the substrate surface. After 1 at% Fe is doped, the crystalline quality and the preferential orientation of ZnO thin film are improved. However, when Fe-doping concentration is above 1 at%, the crystalline quality and the preferential orientation of ZnO thin film is weakened in turn. The surface morphology analyses of the samples show that the ZnO grain sizes tend to decrease with the increase of Fe-doping concentration. Fe-incorporation hardly influences the transmittance in the visible range, but the optical band-gaps of ZnO thin films gradually increase with the improved Fe-doping concentration. The photoluminescence spectra display that all the samples have an ultraviolet emission peak centered at 381 nm and the 1 at% Fe-doped ZnO thin film has the strongest ultraviolet emission peak. The above results suggest that 1 at% Fe-incorporation can improve the crystalline quality and enhance the ultraviolet emission of ZnO thin film.
A counter electrode was prepared for a dye-sensitized solar cell (DSSC) through electrochemical deposition of mesoporous platinum on fluorine-doped tin oxide glass in the presence of a structure-directing nonionic surfactant, octaethylene glycol monohexadecyl ether (C 16 EO 8). The DSSC fabricated with the electrochemically deposited Pt (ED-Pt) counter electrode rendered a higher solar-to-electricity conversion efficiency of 7.6%, compared with approximately 6.4% of the cells fabricated with the sputter-deposited or most commonly-employed thermal deposited Pt counter electrodes. This enhanced efficiency is attributed to the higher short-circuit photocurrent arising from the increases in the active surface area and light reflection as well as the decrease in the sheet resistance of the ED-Pt film, relative to those of the Pt films prepared by the other two deposition methods. The sputter-deposited Pt film yielded almost the same photovoltaic characteristics as the thermal deposited Pt film. The Pt films were characterized by FE-SEM, AFM, cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, sheet resistance measurements, adhesion tests, and light reflection tests.
A study was conducted to investigate the development of a facile,e synthesis of laterally confined two-dimensional (2D) layered SnS2 nanoplates. Laterally confined 2D SnS2 nanoplates were synthesized by using thermal decomposition of the precursor, Sn(S2CNEt 2)4 in an organic solvent at elevated temperature. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) images showed that the SnS2 nanocrystals obtained by the process are 2D hexagonal nanoplates, with a lateral size of of ca. 150 nm and size distribution. The thickness of SnS2 nanoplates was estimated to be ca. 15 nm, according to the (001) peak by Sherrer equation.