•we report a mild electrochemical method to form Al-doped TiO2 nanotube arrays (NTAs).•Al-doped TiO2 NTAs show a highest electrical conductivity of approx. 20 Ω.•The elemental composition of Al-doped TiO2 NTAs were studied by XPS analysis.•Al-doped TiO2 were proved to be excellent supports materials for supercapacitors.Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al–TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g−1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al–TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

Magneli phase titanium sub-oxide conductive ceramic TinO2n−1 was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/TinO2n−1 composites were prepared by the impregnation-reduction method. The electrochemical stability of TinO2n−1 was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V (vs NHE) in 0.5 mol/L H2SO4 aqueous solution. The catalytic activity and stability of the Pt/TinO2n−1 toward the oxygen reduction reaction (ORR) in 0.5 mol/L H2SO4 solution were investigated through the accelerated aging tests (AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V (vs SCE), the specific kinetic current density of the ORR on the Pt/TinO2n−1 is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/TinO2n−1. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on TinO2n−1 remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2 times that of the Pt/TinO2n−1. The superior catalytic stability of Pt/TinO2n−1 toward the ORR could be attributed to the excellent stability of the TinO2n−1 and the electronic interaction between the metals and the support.