Anodic composite deposition of RuO2/reduced graphene oxide/carbon nanotube for advanced supercapacitors

Abstract

Anodic composite deposition is demonstrated to be a unique method for fabricating a ternary ruthenium dioxide/reduced graphene oxide/carbon nanotube (RuO2 • xH2O/rGO/CNT, denoted as RGC) nanocomposite onto Ti as an advanced electrode material for supercapacitors. The rGO/CNT composite in RGCs acts as a conductive backbone to facilitate the electron transport between current collector and RuO2 • xH2O nanoparticles (NPs), revealed by the high total specific capacitance (CS,T = 808 F g-1) of RGC without annealing. The contact resistance among RuO2 • xH2O NPs is improved by low-temperature annealing at 150 °C (RGC-150), which renders slight sintering and enhances the specific capacitance of RuO2 • xH2O to achieve 1200 F g-1. The desirable nanocomposite microstructure of RGC-150 builds up the smooth pathways of both protons and electrons to access the active oxy-ruthenium species. This nanocomposite exhibits an extremely high CS,T of 973 F g-1 at 25 mV s-1 (much higher than 435 F g-1 of an annealed RuO2 • xH2O deposit) and good capacitance retention (60.5% with scan rate varying from 5 to 500 mV s-1), revealing an advanced electrode material for high-performance supercapacitors.