Supercapacitive properties of layered electrodes composed of electrodeposited RuO2 and polyaniline

Layered electrodes of electrodeposited RuO2 (eRuO2) and polyaniline (ePAn) are prepared on a platinum substrate to yield ePAn-on-eRuO2 and eRuO2-on-ePAn electrodes and their supercapacitive properties are investigated. The eRuO2 electrode forms a compact stratified structure with nearly flat surfaces by electrodeposition from a RuCl3·3H2O-based solution, whereas the ePAn electrode forms densely connected particles or particle aggregates by the electrodeposition from aniline solution. In the scan rate range of 20-1000 mV s−1, specific capacitance (810-575 F g−1) of ePAn-on-eRuO2 electrode is superior by the higher probability to occur redox reaction and proton diffusion due to particulate surface and inner pores of the upper layer (ePAn), respectively. In contrast, the eRuO2-on-ePAn electrode loses the specific capacity (680-550 F g−1) but achieves higher capacity retention ratio (81%) by flat compact surface of the upper layer (eRuO2).