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SEM images of (a) WS2 nanosheets at 240 °C for 24 hrs. (b) MoS2/WS2 heterostructures, flower‐shaped microstructure of MoS2 assembled by WS2 nanosheets, synthesis via hydrothermal for 8 hrs at 200° (c) WS2/TiO2 heterostructures, WS2 nanosheets are uniformly distributed on TiO2 nanotubes synthesized via hydrothermal for 8 hrs at 200 °C.
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Two‐dimensional (2D) tungsten disulphide (WS2) based heterostructures with modified interfaces have huge potential for photocatalytic applications. Integrating WS2 with one‐dimensional (1D) titanium dioxide (TiO2) and 2D molybdenum disulphide (MoS2) structures to form heterostructures, enhances its photocatalytic activity. The enrichment in photoca...
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Transition metal dichalcogenide (TMDs) heterostructure, particularly the lateral heterostructure of two different TMDs, is gaining attention as ultrathin photonic devices based on the charge transfer (CT) excitons generated at the junction. However, the characteristics of the interface of the lateral heterostructure, determining the electronic band...
Citations
... Furthermore, peaks at 163.17 eV and 162.07 eV corresponds to S 2p 1/2 and S 2p 3/2 of S orbital. In the corresponding heterostructure a slight shift in binding energy is observed for W and S towards lower region indicating the coupling between WS 2 and TiO 2 components, thus confirming the formation of heterostructure as has been studied before [34,66]. Additionally, spectra of Ti with peaks at 464.4 eV and 458.7 eV corresponding to Ti 2p 1/2 and Ti 2p 3/2 confirms its presence. ...
... Fig. 7 represents the UV absorption spectra for TNR, WNS and WNS/TNR heterostructure. The absorption for pristine samples and heterostructure was found to be in the range 300-800 nm [8,34,58]. The band gaps of TNR, WNS and WNS/TNR were determined using Tauc plots. ...
... To understand the charge flow direction, the band structures of WNS and WNS/TNR were investigated through ultraviolet photoelectron spectroscopy (UPS) (Fig. 8). The work function was determined using the equation reported in literature, considering the laser light (21.22 eV) as incident ultraviolet photons and using the fermi energy (E F ) as well as the cutoff energy of secondary electrons (E cutoff ) [34,[74][75][76]. The magnified view of secondary electron cut off region and valence band edges for WNS and WNS/TNR heterostructure is shown. ...
Hydrogen as a clean fuel is increasingly sought after for its potential to replace non-renewable energy sources, with the hydrogen evolution reaction (HER) presenting a sustainable method for its production. This study focuses on enhancing HER efficiency through the fabrication of a Z-scheme based tungsten di sulfide/titanium di oxide (WS2/TiO2) heterostructure via hydrothermal synthesis. Transition metal dichalcogenides like WS2, known for their unique properties, are integrated with TiO2 nanorods to create a robust photocatalytic system. Characterization techniques such as X-ray diffraction (XRD), Raman spectroscopy, Field-emission scanning electron microscopy (FE-SEM) and Brunauer-Emmett-Teller (BET) were performed. X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS) provided comprehensive insights into the electronic interactions and charge transfer kinetics. A shift in peak positions in XPS spectra indicate the enhancement in catalytic active sites which is in corroboration with the UPS studies. An altered energy environment causing the Z-scheme charge transfer in heterostructure was proved, enhancing the hydrogen production. From the UPS studies, a lower work function for heterostructure i.e. 5.47 eV as compared to 5.5 eV for pristine WS2 indicates improvement in charge transfer. Electrochemical measurements including linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) confirmed the improved HER performance of heterostructure with lower value of onset potential (0.031 V) and charge transfer resistance (3.5 k Ω) as compared to pristine samples. Thus, proving WS2/TiO2 heterostructure to be a potential candidate for sustainable hydrogen production.
... Further, scanning TEM (STEM) images along with energydispersive spectroscopy (EDS) mapping were carried out on the MoS 2 /WS 2 composite. High-annular angle dark-field (HAADF-STEM) allowed the identification of atomic positions with Z differences [35,36], and in particular here, the W sites as shown in Figure 5g. This is confirmed by EDS maps of Mo and W, in Figure 5h and Figure 5i. ...
Visible-light-driven photocatalysis using layered materials has garnered increasing attention regarding the degradation of organic dyes. Herein, transition-metal dichalcogenides MoS 2 and WS 2 prepared by chemical vapor deposition as well as their intermixing are evaluated for photodegradation (PD) of methylene blue under solar simulator irradiation. Our findings revealed that WS 2 exhibited the highest PD efficiency of 67.6% and achieved an impressive PD rate constant of 6.1 × 10 ⁻³ min ⁻¹ . Conversely, MoS 2 displayed a somewhat lower PD performance of 43.5% but demonstrated remarkable stability. The intriguing result of this study relies on the synergetic effect observed when both MoS 2 and WS 2 are combined in a ratio of 20% of MoS 2 and 80% of WS 2 . This precise blend resulted in an optimized PD efficiency and exceptional stability reaching 97% upon several cycles. This finding underscores the advantageous outcomes of intermixing WS 2 and MoS 2 , shedding light on the development of an efficient and enduring photocatalyst for visible-light-driven photodegradation of methylene blue.
Hydrogen, essential for clean and sustainable energy solutions, encounters significant challenges in electrochemical water splitting. This study introduces a Z-Scheme WS2/TiO2 heterostructure synthesized via a hydrothermal method, aimed at enhancing hydrogen evolution reaction (HER) performance through interface engineering. Comprehensive interfacial investigations were conducted by using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and UV–vis spectroscopy. XPS analysis revealed peak shifts in the heterostructure, indicative of electronic modifications at the interface. These shifts enhance active site availability, and charge transfer kinetics also corroborated its UPS and UV–vis studies. The establishment of an intimate interface fostering a Z-scheme charge transfer mechanism has been reported. A lower work function of 4.2 eV suggests improved charge transfer at the interface. Furthermore, the development of an internal electric field to achieve Fermi level equilibrium also led to improved HER performance of the Z-scheme-based heterostructure. The prepared heterostructure demonstrated enhanced HER with a lower onset potential (−0.04 V in light and −0.05 V in dark) as compared to pristine WS2 and a lower charge transfer resistance (36.4 Ω in light and 51.2 Ω in dark), highlighting a promising approach for constructing efficient photoelectrochemical device. The study’s insights into strain-induced effects further underscore the potential of the WS2/TiO2 heterostructure for sustainable energy applications. This result paves the way for constructing the facile and efficient method for generating a photoelectrochemical device with solar-to-hydrogen (STH) efficiency equal to 1.16% determined using the water displacement method.
