Formation of lead by reduction of electrodeposited PbO2: comparison between bulk films and nanowires fabrication

Metallic lead was deposited, both in form of bulk films and nanowire array within pores of anodic alumina membranes, following a new two-step procedure, consisting in anodic electrodeposition of α-PbO₂, followed by its reduction to metallic lead. This method allows to overcome drawbacks of the “direct” electrodeposition of lead from aqueous solution, consisting, essentially, in the formation of dendritic deposits. Here, we report the comparison between results obtained in the two cases and discuss the kinetic of oxide reduction both for films and nanowires. Deposit morphology and structure are also discussed. We have found that reduction of α-PbO₂ films proceeds always at high speed and unitary efficiency, with the formation of polycrystalline compact films. Unfortunately, these films present cracks due to the volume shrinkage accompanying the conversion of α-PbO₂ into Pb metal. In addition, α-PbO₂ nanowires reduction proceeds up to a complete conversion to metallic Pb, which present a characteristic “sausage-like” shape caused by the lower molar volume of metal with respect to oxide.