In this paper, we report two easy and novel approaches to improve the conductivity of titanium dioxide nanotubes as electrochemical supercapacitor electrodes: first, increase the thickness of the TiO2 nanotube arrays (TNTAs), second, the synthesis of hydrogenated TiO2 NTAs. We fabricated TiO2 for 6 h,12 h and 16 h by anodization respectively(the thicknesses of each TNTAs are 4, 9, 40 micrometer when anodization time increases), and then hydrogenated each of them by electrochemical doping for 5s at the same condition. The H- TiO2 NTAs show great improvement of capacitance. For the 4 um H-TiO2, the hydrogenation improved the capacitance up to 7.83 mFcm-2 from CV calculation at a scan rate of 100mvs-1, which is 11 times higher than the capacitance obtained from TiO2 by air-annealed at the same condition. The largest capacitance we obtained is 25.14 mFcm-2 at a scan rate of 100 mvs-1 for 40 um H-TiO2. Hydrogenation produces reactive oxygen vacancies within the lattice by changing to which increase the host material by acting as a donor. The increase of the thickness provides longer tubular channel path and more active surface sites for ion diffusion and charge transfer. This work provide an suitable route for increasing the electrochemical capacitance of supercapacitors.
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