Hydrogenated TiO2@reduced graphene oxide sandwich-like nanosheets for high voltage supercapacitor applications

Abstract

Hydrogenated TiO2 has recently attracted considerable attention as potential electrode materials for supercapacitors due to its abundance, low cost, high conductivity, remarkable rate capability, and outstanding long-term cycling stability. Herein, we demonstrate the synthesis of hydrogenated TiO2 nanoparticles anchored on reduced graphene oxide nanosheets (HTG) in the form of sandwich-like nanosheet composites. Further, we explored their implementation as electrode materials for high voltage, symmetric supercapacitors, operating in the voltage window of 0–1.8 V. The HTGs were prepared by a sol-gel method, followed by hydrogenation in the temperature range 300–500 °C. Of the prepared composites, HTG prepared at 400 °C exhibited the largest specific capacitance of 51 F g−1 at the current density of 1.0 A g−1 and excellent rate capability with 82.5% capacitance retention as the current density increased 40-fold, from 0.5 to 20.0 A g−1. HTG's excellent rate capability was attributed to its sandwich-like nanostructure, in which ultrasmall hydrogenated TiO2 nanoparticles densely anchored onto both surfaces of the two-dimensional reduced graphene oxide sheets. Moreover, HTG-based supercapacitors also exhibited long-term cycling stability with the retention over 80% of its initial capacitance after 10,000 cycles. These properties suggest that HTG is a promising electrode material for the scalable manufacture of high-performance supercapacitors.