Effect of the current density on electrodepositing alpha-lead dioxide coating on aluminum substrate

The α-PbO2 electrodes are prepared by anodic electrodeposition on A1/conductive coating electrode from alkaline plumbite solutions in order to investigate the effect of the different current densities on the properties of α-PbO2 electrodes. The physicochemical properties of the α-PbO2 electrodes are analyzed by using SEM, EDS, XRD, Tafel plot, linear sweep voltammetry (LSV) and A.C. impedance. A compact and uniform layer of lead dioxide was obtained at the current density of 3 mA·cm−2. A further increase in current density results in smaller particles with high porosity. EDS and XRD analyses have shown that the PbO2 deposited in alkaline conditions is highly non stoichiometric, and the PbO impurities are formed on the surface layer besides the α-PbO2. The corrosion resistance of α-PbO2 at the low current density is superior to that of the high current density. It can be attributed to a porous layer of deposited films at high current densities. When used as anodes for oxygen evolution in aqueous Zn2+ 50 g·L−1, H2SO4 150 g·L−1, the Al/conductive coating/α-PbO2 exhibits lower potential compared to Pb electrode. Al/conductive coating/α-PbO2 electrode with the best electrocatalytic activity was obtained at current density of 1 mA cm−2. The lowest roughness factor was obtained at 1 mA cm−2.