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 (13.13wt%) and Co (2.89wt%)] or RuO2, exhibited a similar specific capacitance (∼620Fg−1) at low potential scan rates (10mVs−1). However, at higher scan rates (500mVs−1) the mixed metal oxide electrode showed superior performance (570Fg−1) when compared to the RuO2 electrode (475Fg−1). This increase in capacitance at high scan rates is attributed to the role of the Co in providing enhanced electronic conduction.