Abstract:

This study used the target-controlled anodizing process for the controllable fabrication of TiO₂ nanotube arrays (TiO₂ NTAs) film substrate with large specific surface area and well-separated nanotubes. After annealing crystallization, TiO₂ NTAs were successively functional modified by electrochemical hydrogenation and sequential chemical bath deposition of high specific capacitance MnO₂ nanoparticles onto both the outer and inner surfaces of the nanotubes, thus constructing the heterostructured MnO₂/H-TiO₂ NTAs electrode. The as-prepared samples were fully characterized by field emission scanning electron microscopy (FESEM), highresolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy. The supercapacitive performance and stability of the resulting samples were systematically evaluated using electrochemical workstation. The results from the current study revealed that conductivity and electrochemical properties of H-TiO₂ NTAs were dramatically enhanced through electrochemical hydrogenation and the specific capacitance of H-TiO₂ NTAs could achieve 7.5 mF·cm^-2 at current density of 0.2 mA·cm^-2, which is almost 75 times the performance of TiO₂ NTAs (0.1 mF·cm^-2). Furthermore, the specific capacitance of MnO₂/H-TiO₂ NTAs-2 could achieve 481.26 F·g^-1 at a current density of 3 mA·mg^-1 as well as outstanding long-term cycling stability with only 11% reduction of initial specific capacitance at a current density of 5 mA·mg^-1 after 1000 cycles.

Key words: TiO₂ nanotube array, Hydrogenation, MnO₂, Electrochemistry, Supercapacitive performance