Hydrogenated TiO2 Nanotube Arrays for Supercapacitors

TLDR: The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors.

Abstract: We report a new and general strategy for improving the capacitive properties of TiO2 materials for supercapacitors, involving the synthesis of hydrogenated TiO2 nanotube arrays (NTAs). The hydrogenated TiO2 (denoted as H–TiO2) were obtained by calcination of anodized TiO2 NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H–TiO2 NTAs prepared at 400 °C yields the largest specific capacitance of 3.24 mF cm–2 at a scan rate of 100 mV s–1, which is 40 times higher than the capacitance obtained from air-annealed TiO2 NTAs at the same conditions. Importantly, H–TiO2 NTAs also show remarkable rate capability with 68% areal capacitance retained when the scan rate increase from 10 to 1000 mV s–1, as well as outstanding long-term cycling stability with only 3.1% reduction of initial specific capacitance after 10 000 cycles. The prominent electrochemical capacitive properties of H–TiO2 are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO2 surfa...