Integration of mesoporous nickel cobalt oxide nanosheets with ultrathin layer carbon wrapped TiO2 nanotube arrays for high-performance supercapacitors

Abstract

Decorated TiO₂ nanotube array-based electrodes for supercapacitors are successfully fabricated by a facile and green process in this paper. Firstly, TiO₂ nanotube arrays are modified with ultrathin carbon layers by in situ pyrolysis with residual ethylene glycol from anodization as a carbon resource, then electroactive materials, nickel cobalt oxides with different stoichiometric nickel and cobalt contents, are synthesized by chemical bath deposition and a controlled post-calcination process. The sample demonstrates a superb specific capacitance of 934.9 F g⁻¹ at a current density of 2 A g⁻¹ and a better rate capability of 865.8 F g⁻¹ at 20 A g⁻¹ while maintaining 92.6% capacity after 5000 cycles at a high current density of 10 A g⁻¹. The outstanding supercapacitive performance is attributed to the unique hierarchical mesoporous architectures and the desirable design of the nanocomposites, and it also suggests that carbon modified TiO₂ nanotube arrays decorated with nickel cobalt oxides are promising candidates for supercapacitor applications.