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