The fabrication of lead dioxide layers on a titanium substrate

It is shown that stable and active lead dioxide on titanium anodes (including mesh electrodes) may be fabricated by appropriate pretreatment of the substrate and a strategy involving the anodic deposition of two PbO2 layers-a thick underlayer with the lead dioxide doped with fluoride and iron and a top layer with the lead dioxide doped with bismuth. Periods on open circuit, especially in solutions containing an oxidisable organic or inorganic species must, however, be avoided since all forms of PbO2 are reducible unless protected by an anodic current; the rates of the reduction does depend on the medium, the dopants in the PbO2 and the morphology of the layer. It is also shown that, as at gold substrates, the morphology of the PbO2 layer on titanium (consequently, their properties including adhesion and electrocatalytic activity) depend strongly on the deposition conditions including the bath composition (including Pb(II) concentration, acid concentration, concentration and choice of dopantion), temperature, current density and deposition charge. (c) 2006 Elsevier Ltd. All rights reserved.