Effects of Tungsten Carbide on the Electrocatalytic Activity of PbO2-WC Composite Inert Anodes during Zinc Electrowinning

Abstract

β-PbO2-WC composite electrodes were prepared via direct electrodeposition in a lead nitrate solution that contains WC microparticles. The effect of WC concentration in the composite anode material was emphasized. The surface microstructure was characterized by scanning electron microscopy (SEM), and the electrocatalysis of oxygen evolution behavior was investigated using anodic polarization curves, cyclic voltammetry curves and electrochemical impedance spectroscopic (EIS) measurements in a synthetic zinc electrowinning electrolyte of 50 g·L−1 Zn2+ and 150 g·L−1 H2SO4 at 40°C. The results show that the addition of WC can clearly decrease the grain size of PbO2 electrodes, and the electrodes become more compact. The addition of WC can increase the exchange current density j0 of a composite electrode during the process of oxygen evolution, reduce the apparent activation energy Ea of the oxygen evolution reaction, increase the values of electric double layer capacitance Cdl during the charging process, increase the electric double layer capacitance Qdl of oxygen evolution reaction process, and reduce the values of charge transfer resistance Rct; and also can improve the electrocatalytic stability. The doping of WC in the Ti/β-PbO2 composite electrode can effectively improve the electrode coating microstructure, increase the electrocatalytic activity of the oxygen evolution reaction in the electrolytic zinc liquid and exert positive effects on the application of the composite electrode.