Vertically aligned mixed V 2O 5-TiO 2 nanotube arrays for supercapacitor applications

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany.
Chemical Communications (Impact Factor: 6.83). 07/2011; 47(27). DOI: 10.1039/c1cc11811k


Highly ordered mixed V 2O 5-TiO 2 nanotubes can be formed by self-organizing anodization of Ti-V alloys with vanadium content of up to 18 at%. In the resulting oxide nanotube arrays, the vanadium is electrochemically switchable leading to a specific capacitance that can reach up to 220 F g -1 and an energy density of 19.56 Wh kg -1 with perfect reversibility and long-term stability. Thus these mixed oxide nanotubes may be considered as a promising candidate for supercapacitors. © 2011 The Royal Society of Chemistry.

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    • "V 2 O 5 is a wide band gap n-type semiconductor material [2] with particularly useful properties due to the fact that charge transport is performed by means of polarons, as has been reported for both the bulk singlecrystal structure [3], and the amorphous V 2 O 5 layers [4] [5]. These properties make V 2 O 5 thin films candidate for many practical uses, such as a catalyst material in gas sensors [6] [7], as a dielectric constituent material in super capacitors [8], as a high capacity storage medium in Li-ion batteries , as a cathode in these batteries [9], or as a thermo-resistive material in thermal infrared detectors [10]. V 2 O 5 thin films can be prepared using various deposition techniques [11], being sputtering the preferred method due to the good surface uniformity provided. "
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    ABSTRACT: The present study investigates the main electrical transport mechanism in V 2 O 5 thin films deposited by RF mag-netron sputtering on the basis of the Mott's small polaron hopping model. The material under test was obtained at room temperature from a V 2 O 5 target and then oxidized at high temperature under air atmosphere to obtain the desired V 2 O 5 phase. The dependence of the electrical conductivity of the V 2 O 5 thin films with temperature was analyzed using the Mott's small polarons hopping transport model under the Schnakenberg form. Model results suggest a polaron binding energy W H = 0.1682 eV, with a structural disorder energy W D = 0.2241 eV and an optical phonon frequency ν 0 = 0.468 × 10 13 s −1. These results are in agreement with data reported in literature for single crystal V 2 O 5. However, the carrier mobility μ = 1.5019 × 10 −5 cm 2 /Vs computed in the non-adiabatic regime is significantly smaller than that of the single crystal, suggesting a strong electron–phonon coupling in the V 2 O 5 thin films obtained with the proposed deposition method.
    Thin Solid Films 08/2015; 589:730-734. DOI:10.1016/j.tsf.2015.06.048 · 1.76 Impact Factor
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    • "The composite 3-D nanostructured electrodes have synergic contribution to specific capacitance based on their electroactive functions which boost energy density, and their nanoarchitecture have the ability to mitigate the ion diffusion limitation thereby enhancing the power density. In the past, 3-D nanotube polymers, PPy-PANI [33] polymer-metal oxides, TiO2-PPy [34,35], ZnO-PPy [36], TiO2-NiO [23], and TiO2-V2O5[37] have been reported. "
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    ABSTRACT: Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 for open pore and approximately 180 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles.
    Nanoscale Research Letters 08/2014; 9(1):453. DOI:10.1186/1556-276X-9-453 · 2.78 Impact Factor
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    • "The results demonstrate, that alkaline metal ions indeed participate in the redox reaction of MnO 2 . V 2 O 5 , because of its high energy density, low cost, and capability of fast charge–discharge, is another promising candidate material for both lithium ion batteries and supercapacitors [18] [19] [20] [21] [22] [23]. In aqueous electrolyte solutions, V 2 O 5 has been reported to exhibit the highest capacitance in KCl solution compared with other solutions of e.g. "
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    ABSTRACT: The electrochemical behavior of V2O5·0.6H2O nanoribbons in 0.5 mol/L Li2SO4, Na2SO4, and K2SO4 aqueous solutions is compared. The electrochemical reaction of V2O5·0.6H2O in these neutral aqueous electrolyte solutions was elucidated by analyzing the different electrochemical behavior, structural and composition changes of V2O5·0.6H2O electrodes during charge/discharge. Results show, that V2O5·0.6H2O exhibits the largest specific capacity in K2SO4 electrolyte attributed to the most facile intercalation/deintercalation of K+-ions into/from the interlayer space of V2O5·0.6H2O.
    Electrochimica Acta 04/2013; 96:8–12. DOI:10.1016/j.electacta.2013.02.078 · 4.50 Impact Factor
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