In order to develop an energy-saving insoluble anode for Zn electrowinning, Pb-based anodes in which catalyst powders of low oxygen evolution overpotential were spread over the Pb substrate were prepared by powder-rolling method and the effect of the catalyst powder on lowering the anode potential was investigated. It was clearly shown by galvanostatic electrolysis and anode polarization measurement that the RuO2 powder dispersed to the Pb substrate was effective in reduction of oxygen evolution overpotential. The anode potential of Pb-RuO2 anode fell remarkably around RuO2 content of 0.60 mass%, and the anode potential of the Pb-based anodes containing 0.70-1.50 mass%RuO2 was 300-350 mV lower than that of the pure Pb anode. The activation energy of the oxygen evolution reaction of Pb-RuO2 anodes containing 0.50 or 1.00 mass%RuO2 was only 24-26 kJ mol-1, whereas those of pure Pb and Pb-0.70mass%Ag anodes were 62.7 and 35.5 kJ mol-1 respectively. Therefore, it was judged that RuO2 could accelerate the oxygen evolution reaction more efficiently than Ag as the electrode catalyst. XPS analysis also showed that the existence ratio of PbO2 on the Pb-RuO2 anode surface after electrolysis for 18.0 ks was higher than those of the pure Pb and the Pb-0.70mass%Ag anodes. Consequently, the chemical conversion from Pb to PbO2 might be also concerned with lowering the anode potential of the Pb-based anodes.
