Capacitive properties of RuO2 and Ru–Co mixed oxide deposited on single-walled carbon nanotubes for high-performance supercapacitors

Composite electrodes for use in redox supercapacitors were prepared by electrochemical deposition of RuO2 or the co-deposition of Ru–Co mixed oxides on the surface of single-walled carbon nanotubes. Electrodes coated with the Ru–Co mixed oxide [Ru (13.13 wt%) and Co (2.89 wt%)] or RuO2, exhibited a similar specific capacitance (∼620 F g−1) at low potential scan rates (10 mV s−1). However, at higher scan rates (500 mV s−1) the mixed metal oxide electrode showed superior performance (570 F g−1) when compared to the RuO2 electrode (475 F g−1). This increase in capacitance at high scan rates is attributed to the role of the Co in providing enhanced electronic conduction.