Hydrogenated TiO₂ Nanotube Arrays for Supercapacitors

Abstract

We report a new and general strategy for improving the capacitive properties of TiO(2) materials for supercapacitors, involving the synthesis of hydrogenated TiO(2) nanotube arrays (NTAs). The hydrogenated TiO(2) (denoted as H-TiO(2)) were obtained by calcination of anodized TiO(2) NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H-TiO(2) 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 TiO(2) NTAs at the same conditions. Importantly, H-TiO(2) 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-TiO(2) are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO(2) surface, as a result of hydrogenation. Furthermore, we demonstrate that H-TiO(2) NTAs is a good scaffold to support MnO(2) nanoparticles. The capacitor electrodes made by electrochemical deposition of MnO(2) nanoparticles on H-TiO(2) NTAs achieve a remarkable specific capacitance of 912 F g(-1) at a scan rate of 10 mV s(-1) (based on the mass of MnO(2)). The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors.

“Black” TiO2 Nanotubes Formed by High-Energy Proton Implantation Show Noble-Metal-co-Catalyst Free Photocatalytic H2-Evolution

“…[12][13][14][15][16]) -such material was reported to cause a similar effect on the Pt-co-catalyzed photocatalytic H 2 -production or when used in a range of other electrochemical applications [17][18][19].…”

Transmission electron microscopy analysis of some transition metal compounds for energy storage and conversion

“…However, as an electrode material for SCs, TiO 2 suffers from relatively low electrical conductivity and poor electrochemical activity [101]. Recent reports demonstrated that introducing defects in TiO 2 can address these limits and thus improve specific capacitance and stability of TiO 2 materials [102,103]. The detailed microstructural investigation is critical to understand how the defect structure influences the electrical conductivity and electrochemical activity of TiO 2 .…”

“…The aberration-corrected high-resolution TEM image revealed hillocks, terraces and surface corrugations as well as lattice bending, which offer openings to Li diffusion channels and thus facilitating the reversible Li incorporation. Chen et al [105] presented HRTEM analysis of the surface M A N U S C R I P T A C C E P T E D Another example of characterizing hydrogenated TiO 2 was presented by Lu [102].…”

“…Combined with XPS studies that identified the formation of Ti 3+ ions [102], it is speculated that the dislocation defects could possibly be attributed to the oxygen vacancies.…”

NH3 treatment of TiO2 nanotubes: from N-doping to semimetallic conductivity

“…3c) shows a larger difference between the nitrided sample and the doped or native material. The nitrided electrode exhibits the obvious featureless shape of a double layer capacitor with a specific capacitance of 100 F g À1 at 100 mV s À1 -indicating a fast and high capacitance response for these nanostructured conductive electrodes (in fact, the current is higher than that reported under identical conditions for the best tube modification 36 ). This suggests that while the semiconductive materials capacitance values are partially dominated by their space charge layers, for the nitrided sample a metallic behavior (dominated by the Helmholtz layer) is observed.…”