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ABSTRACT: The areal capacity of lithium-ion microbatteies (LIMBs) can be potentially increased by adopting a three-dimensional (3D) architectured electrode. Herein, we report the novel 3D Ni/SnOx/C hybrid nanostructured arrays that were built directly on current collectors via a facile hydrothermal method followed by a calcination-reduction process. Branched SnO2 nanorods grew uniformly on Ni2(OH)2CO3 nanowall arrays, resulting in the formation of precursors with a 3D interconnected architecture. By using ethylene glycol as the reducing agent, the glucose-coated SnO2/Ni2(OH)2CO3 precursors were evolved into an interesting 3D Ni/SnOx/C hybrid nanostructured arrays within the calcination treatment. Compared to conventional 2D SnOx/C nanorod arrays, the electrode of 3D Ni/SnOx/C hybrid nanostructured arrays exhibited enhanced lithium storage capacity per unit area, preferable rate capability and improved cycling performance when tested for LIMBs. The superior performance might be attributed to the open-up Ni frameworks that can not only serve as effective channels for electrons transport and Li+ diffusion but also help to accommodate the large volume changes upon lithiation/delithiation.
ACS Applied Materials & Interfaces 03/2013; · 4.53 Impact Factor
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ABSTRACT: Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed.
Advanced Materials 08/2012; 24(38):5166-80. · 13.88 Impact Factor
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ABSTRACT: A novel evolution strategy has been put forward to build a 3D interconnected core-shell Ni/MnO(2) hybrid on a current collector, which demonstrated stable cyclic performance and good rate capabilities when applied as the anode for Li-ion batteries.
Chemical Communications 06/2012; 48(60):7471-3. · 6.17 Impact Factor
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ABSTRACT: Carbon-coated SnO2 nanorod array directly grown on the substrate has been prepared by a two-step hydrothermal method for anode material of lithium-ion
batteries (LIBs). The structural, morphological and electrochemical properties were investigated by means of X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurement. When used
as anodes for LIBs with high current density, as-obtained array reveals excellent cycling stability and rate capability. This
straightforward approach can be extended to the synthesis of other carbon-coated metal oxides for application of LIBs.
KeywordsCarbon-coated SnO2 nanorod array-Hydrothermal method-LIBs-Anode material-Array architecture
Nanoscale Research Letters 04/2012; 5(3):649-653. · 2.73 Impact Factor
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ABSTRACT: We report a novel hydrothermal method for the synthesis of a Cu@C nanotube array on a centimeter-scale substrate for the first time. In this hydrothermal reaction process, employing the carbon coated ZnO nanorod array as an inexpensive and partially sacrificial template, along with the ZnO dissolving in the alkaline atmosphere, the formed Cu particles deposit and grow on the carbon surface gradually. Importantly, the carbon shell of the template is not only essential to the preservation of the array configuration, but also makes a significant contribution to the final nanostructure. Such a method provides a morphology-reservation transformation when various shaped carbon-containing templates are adopted. Moreover, this designed Cu@C array has been demonstrated as an excellent electrode material for an enzyme-free glucose sensor in terms of sensitivity (1200 µA mM( - 1) cm( - 2)) and significantly lower applied potential (-0.2 V). Our results present the first preparation of the Cu@C composite nanotube array and may open up an opportunity for rational design of advanced electrode materials for enzyme-free glucose sensors.
Nanotechnology 09/2011; 22(37):375303. · 3.98 Impact Factor
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ABSTRACT: A composite bionanomaterial was prepared by combining Nafion, flowerlike cobalt oxide (CoO) nanoparticles, hemoglobin (Hb), and ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate. Then it was further applied on the surface of a carbon ionic liquid working electrode fabricated with 1-ethyl-3-methylimidazolium ethylsulfate as the modifier. Ultraviolet–visible and Fourier transform infrared spectroscopic results indicated that Hb molecules in the composite film retained the native structure. Cyclic voltammetric results showed that a pair of well-defined redox peaks appeared in 0.1 mol L–1 pH 4.0 phosphate buffer solution, indicating that the direct electron transfer of Hb with the underlying electrode was realized. The results could be attributed to the synergistic effect of CoO nanoflower and IL in the composite film, which provided a specific microenvironment to keep the native structure of Hb and promoted the electron transfer rate of Hb. The electrochemical parameters of Hb on the modified electrode were carefully calculated. The composite material modified electrode showed excellent electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid and H2O2, which exhibited advantages such as high sensitivity, good stability, and wide dynamic range. Therefore, it has potential application in third-generation electrochemical biosensors.
06/2011;
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ABSTRACT: Large-scale uniform α-Co(OH)₂ nanowire arrays (NWAs) with an average length of ∼20 μm grown on pyrolytic graphite (PG) were successfully synthesized by a hydrothermal method at 120 °C. Ultrasonication test was carried out toward the as-made nanoarray products and the result demonstrated their robust adhesion to graphitic substrate. After 300 s of sonication testing, α-Co(OH)₂ NWAs could still possess both integrated one-dimensional (1D) nanoarray architecture and good electronic connections with current collector. When investigated as electrochemical pseudocapacitor electrodes, α-Co(OH)₂ NWAs exhibited good energy-storage performance in terms of high specific capacitance of 642.5 F/g, good rate capability, and excellent capacity retention. Our work not only presents a cost-effective and scale-up synthetic method for α-Co(OH)₂ NWAs but also holds promise in general synthesis of long arrays of other metal hydroxides/oxide (TiO₂, Fe₂O₃, SnO₂, etc.) nanostructures on PG substrate by using α-Co(OH)₂ NWAs as sacrificial templates.
ACS Applied Materials & Interfaces 01/2011; 3(1):99-103. · 4.53 Impact Factor
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ABSTRACT: We report here for the first time the synthesis of two novel hierarchical homogeneous nanoarchitectures of TiO2 nanorods branched TiO2 nanotube arrays (BTs) and P25-coated TiO2 nanotube arrays (PCTs) using two-step method including electrochemical anodization and hydrothermal modification process. Then the photocurrent densities versus applied potentials of BTs, PCTs, and pure TiO2 nanotube arrays (TNTAs) were investigated as well. Interestingly, at -0.11 V and under the same illumination condition, the photocurrent densities of BTs and PCTs show more than 1.5 and 1 times higher than that of pure TNTAs, respectively, which can be mainly attributed to significant improvement of the light-absorbing and charge-harvesting efficiency resulting from both larger and rougher surface areas of BTs and PCTs. Furthermore, these dramatic improvements suggest that BTs and PCTs will achieve better photoelectric conversion efficiency and become the promising candidates for applications in DSSCs, sensors, and photocatalysis.
Nanoscale Research Letters 01/2011; 6(1):91. · 2.73 Impact Factor
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ABSTRACT: ZnO nanorod array grown directly on an inert alloy substrate has been modified with carbon by a simple immersion-calcination route and further used as the working electrode to construct a hydrazine sensor. The C@ZnO nanorod array-based sensor demonstrates a very high sensitivity of 9.4 muA muM(-1) cm(-2) and a low detection limit of 0.1 muM. The improved electrochemical properties are proposed to result from the synergy between the carbon layer and nanorod array, which can increase the ZnO electrocatalytic activity and promote the electron transport along the one-dimensional (1D) pathway, respectively. In particular, the carbon layer on ZnO nanorods also improves the sensor stability for successive usage due to the high chemical stability of carbon. The present study demonstrates the facile design of a promising electrode material for a hydrazine sensor and sheds light on the performance optimization of other electrochemical devices.
Dalton Transactions 10/2010; 39(37):8693-7. · 3.84 Impact Factor
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ABSTRACT: Lithium ion battery (LIB) is potentially one of the most attractive energy storage devices. To meet the demands of future high-power and high-energy density requirements in both thin-film microbatteries and conventional batteries, it is challenging to explore novel nanostructured anode materials instead of conventional graphite. Compared to traditional electrodes based on nanostructure powder paste, directly grown ordered nanostructure array electrodes not only simplify the electrode processing, but also offer remarkable advantages such as fast electron transport/collection and ion diffusion, sufficient electrochemical reaction of individual nanostructures, enhanced material-electrolyte contact area and facile accommodation of the strains caused by lithium intercalation and de-intercalation. This article provides a brief overview of the present status in the area of LIB anodes based on one-dimensional nanostructure arrays growing directly on conductive inert metal substrates, with particular attention to metal oxides synthesized by an anodized alumina membrane (AAM)-free solution-based or hydrothermal methods. Both the scientific developments and the techniques and challenges are critically analyzed.
Nanoscale 10/2010; 3(1):45-58. · 5.91 Impact Factor
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ABSTRACT: In this paper an urchinlike MnO(2) nanoparticle was synthesized by hydrothermal method and applied to the protein electrochemistry for the first time. By using a carbon ionic liquid electrode (CILE) as the basal electrode, hemoglobin (Hb) was immobilized on the surface of CILE with chitosan (CTS) and MnO(2) nanoparticle composite materials. Spectroscopic results indicated that Hb molecules retained its native structure in the composite film. A pair of well-defined redox peaks appeared on the cyclic voltammogram with the formal peak potential as -0.180 V (vs. SCE), which indicated that direct electron transfer of Hb was realized on the modified electrode. The result can be attributed to the specific characteristic of MnO(2) nanoparticle and the advantages of CILE, which facilitated the electron transfer rate. The fabricated CTS-MnO(2)-Hb/CILE showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA). Under the optimal conditions the catalytic current was in linear to TCA concentration in the range from 0.5 to 16.0 mmol L(-1) with the detection limit calculated as 0.167 mmol L(-1) (3σ). The result indicated that urchinlike MnO(2) nanoparticle had the potential application in the third generation electrochemical biosensors.
Biosensors & bioelectronics 09/2010; 26(5):2119-24. · 5.43 Impact Factor
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ABSTRACT: We report an effective approach for the growth of vertically aligned one-dimensional (1D) ZnO nanostructures on various substrates (ceramic, silicon, quartz glass and metal) in mild solutions (T = 95 °C) without any seeds or catalysts. With the measurements of SEM, FT-IR, XRD and TEM, the novel growth mechanism of the ZnO nanorod arrays has been discussed in detail. The results show that the key of the ZnO direct growth on the demanded substrate is the introduction of glucose into the Zn2+-contained solution, which functionalizes the substrate, leading to the ZnO heterogeneous nucleation on the substrate surface. Particularly noteworthy is that the obtained ZnO is coated with carbonaceous species layer; this layer can be carbonized at high temperature in nitrogen to form core-shell composite structures, or removed by oxidation according to different application requirements. Furthermore, it is found that carbon-coated ZnO composite nanostructure shows superior UV excitonic emissions over the pristine ZnO. We believe that our approach presents a general economical route toward mass production of controllable ZnO-based arrays and will facilitate flexible design of device architectures for nanoelectronics.
Science of Advanced Materials 08/2010; 2(3):396-401. · 3.31 Impact Factor
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ABSTRACT: A new composite material consisted of hyaluronic acid (HA), ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF(4)) and cadmium sulfide (CdS) nanorod was fabricated and used for the immobilization of horseradish peroxidase (HRP) on the surface of a carbon ionic liquid electrode (CILE), which was prepared with 1-ethyl-3-methyl-imidazolium ethylsulphate ([EMIM]EtOSO(3)) as modifier. Spectroscopic results indicated that HRP remained its native structure in the composite film. Based on the synergistic effect of the materials used, an obvious promotion to the direct electron transfer efficient between HRP and CILE was achieved with a pair of well-defined redox peaks appeared in 0.1 mol L(-1) phosphate buffer solution, indicating the realization of the direct electrochemistry of HRP. The immobilized HRP showed good electrocatalytic activity towards the reduction of trichloroacetic acid and H(2)O(2) with the electrochemical parameters calculated. Based on the fabricated electrode, a new third-generation electrochemical biosensor was constructed with good stability and reproducibility.
Analytica chimica acta 06/2010; 670(1-2):51-6. · 4.31 Impact Factor
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ABSTRACT: Carbon-modified Bi(2)WO(6) (C-Bi(2)WO(6)) nanostructures were synthesized via a hydrothermal process in the presence of glucose followed by the calcination in Ar gas at 500 degrees C. The morphologies and crystallinity of Bi(2)WO(6) and the nature of carbon in the composites obtained with different glucose amounts were characterized. Raman spectrum analysis, electron microscopy results and light absorption of C-Bi(2)WO(6) at wavelengths larger than 450 nm clearly confirmed the carbon modification. Further results indicated that glucose did not affect the final crystalline structure or the band gap of Bi(2)WO(6), but it had great influences on the photocatalytic activity of Bi(2)WO(6) towards rhodamine-B (RhB) degradation. When the glucose amount was less than 0.04 g, the photoactivity was enhanced step by step with an increase in the glucose amount. The improved photocatalytic performance could be ascribed to the enhanced photogenerated electron-hole separation and more RhB adsorption associated with carbon. However, when the glucose amount was higher than 0.04 g, the photocatalytic property dramatically decreased due to the severe absorption of almost incident light by carbon, which hindered the accessibility of light to Bi(2)WO(6). Our work provides an alternative way to improve the photoactivity of Bi(2)WO(6) nanomaterials.
Dalton Transactions 04/2010; 39(14):3420-5. · 3.84 Impact Factor
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ABSTRACT: SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP) immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM-1 cm-2), low detection limit (0.2 μM) and high selectivity with the apparent Michaelis-Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.
Nanoscale Research Letters 01/2010; 5(7):1177-81. · 2.73 Impact Factor
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ABSTRACT: We report for the first time a facile and direct synthesis of large-scale cobalt monoxide (CoO) porous nanowire arrays (NWAs) with robust mechanical adhesion to flexible conductive substrate (Ti foil) by a two-step method. Significantly raw salt cubic CoO of high quality from the complete pyrolysis of cobalt-hydroxide-carbonate (precursor) is achieved. When serving as lithium-ion battery electrodes in the absence of any ancillary materials (carbon black and binder), the as-obtained well-aligned CoO NWAs, possessing both the completely reversible electrochemical properties and unique advantages originating from integrated one-dimensional (1D) nanostructured architecture, exhibit good high-rate capability at a rate of 1 C (716 mA/g), 2 C (1432 mA/g), 4 C (2864 mA/g), and 6 C (4296 mA/g), respectively.
12/2009;
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ABSTRACT: High surface area ZnO-carbon composite tubular arrays on a ceramic substrate were successfully synthesized by a hydrothermal process and a subsequent nanoscale diffusion-related reaction within the carbonaceous species-coated ZnO rod arrays during 900 degrees C annealing.
Chemical Communications 09/2009; · 6.17 Impact Factor
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ABSTRACT: Carbon/ZnO nanorod arrays on nickel substrate have been fabricated over a large area by the simple carbonization of preadsorbed glucose on ZnO arrays at 500 °C in argon gas. The uniform coating of average 6 nm carbon shell on ZnO nanorod surface is confirmed. The novel array architecture possesses both the electroactivity of carbon and the electrochemical advantages of array structure on conductive substrate. When used as anode for Li ion batteries, it displays significantly improved performance in terms of cycling stability and rate capability. The observed lithium storage ability ranges among the best reported to date for ZnO-based anode. We believe that the novel carbon-coating route is general and can be extendable to other metal oxide nanoarray electrodes.
03/2009;
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ABSTRACT: Bi2WO6 hierarchical structures constructed by a number of square nanoplates of average approximately 70 nm in side length and approximately 25 nm in thickness have been synthesized by a hydrothermal method at 180 degrees C. The single-crystal subunit nanoplates with (002) as their two-dimensional (2D) surfaces assembled orderly using both their edges and faces into free-standing films. It was found that the self-assembled growth of these hierarchical structures strongly depended on surfactant Cetyl Trimethyl Ammonium Bromide (CTAB), the amounts of the starting materials and the molar ratio of precursors (Bi3+ to WO4(2-)), etc. The growth mechanism was discussed based on the comparative experimental results.
Journal of Nanoscience and Nanotechnology 03/2009; 9(2):1530-4. · 1.56 Impact Factor
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ABSTRACT: a b s t r a c t We report here the direct electron transfer of GOD and a novel glucose biosensor based on carbon-dec-orated ZnO(C–ZnO) nanowire array electrode. The C–ZnO nanowire array provides a novel platform for fast direct electrochemistry of GOD, and its based biosensor shows very high sensitivity and low detec-tion limit. Based on the direct electrochemistry of horseradish peroxidase (HRP), the H 2 O 2 biosensing application is further demonstrated using this new C–ZnO array architecture. The high conductivity of carbon and good electron transfer capability of ZnO nanowires, along with their low cost and biocompat-ibility make the C–ZnO nanowire array a promising platform for direct electrochemistry of enzymes and mediator-free enzymatic biosensors. Ó 2008 Published by Elsevier B.V.
12/2008;
