Electrochemical behavior of Pb-Ag-Nd alloy during pulse current polarization in H2SO4 solution
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Henan Yuguang Zinc Industry Co. Ltd., Jiyuan 459000, China)
2. Henan Yuguang Zinc Industry Co. Ltd., Jiyuan 459000, China)
Abstract: The anodic layer and oxygen evolution behavior of Pb-Ag-Nd alloy during pulse current polarization and constant current polarization in 160 g/L H2SO4 solution was comparatively investigated by chronopotentiometry, SEM, XRD, EIS and Tafel techniques. The results show that the anodic layer on Pb-Ag-Nd alloy formed through pulse current polarization is more intact and presents fewer micro-holes than that formed through constant current polarization. This could be attributed to the low current density period, which works as a ‘recovery period’. During this period, the oxygen evolution reaction is less intense, which benefits the recovery of porous anodic layer. Pb-Ag-Nd anode also shows a lower anodic potential during pulse current polarization, which is in accordance with its smaller charge transfer resistance and smaller Tafel slope coefficient at high over-potential region. The lower anodic potential could be ascribed to the higher concentration of PbO2 in the anodic layer, which promotes the formation of more reactive sites for the oxygen evolution reaction.
Key words: Pb-based anode; pulse current polarization; oxygen evolution behavior; anodic layer