Electrochemical hydrogenated TiO₂ nanotube arrays decorated with 3D cotton-like porous MnO₂ enables superior supercapacitive performance

Highly ordered TiO₂ nanotube arrays (TNTAs) have shown great promise to serve as an efficient current collector as well as an outstanding support for the application of constructing high performance supercapacitor electrode materials. In this study, a novel-structured MnO₂/EH-TNTAs electrode with superior supercapacitive performance was developed by galvanostatic electrodeposition of MnO₂ nanoflakes onto both the outer and inner walls of electrochemically hydrogenated TNTAs (EH-TNTAs). The as-fabricated MnO₂/EH-TNTAs electrode could achieve a specific capacitance of up to 650.0 F g^-1 at 1.0 A g^-1 with 86.9% of the initial capacitance remaining after 5000 charge/discharge cycles at 5 A g^-1, outperforming other reported TNTAs-based electrodes. The prominent supercapacitive performance of MnO₂/EH-TNTAs electrode could be attributed to the unique 3D cotton-like porous structure and high specific surface area of MnO₂ deposit as well as the remarkably improved electrical conductivity and electrochemical performances of EH-TNTAs induced by the introduction of oxygen vacancies during the electrochemical hydrogenation process. This work offers theoretical insight and practical guidelines for TNTAs-based electrodes applied for high-performance supercapacitors as well as other energy storage devices.