Effect of antimony on the reduction of anodic PbO 2 film on Pb‐Sb alloys in sulfuric acid solution

The reduction processes of anodic PbO 2 films formed on Pb‐Sb alloys in 4.5 mol.dm −3 H 2 SO 4 solution at 1.4 V( vs. Hg/Hg 2 SO 4 ) for 1 h have been investigated by photocurrent method, chronoamperometry, linear sweep voltammetry as well as X‐ray diffractometry. It was found that the reduction of most of the β‐PbO 2 and part of the α‐PbO 2 to PbSO 4 can be completed within 1 s between 0.9 V and 1.0 V( vs. Hg/Hg 2 SO 4 ) and proceeds much faster than that of the remaining α‐PbO 2 into photoactive α‐PbO x (1 < x < 1.4). The presence of antimony in the alloy retards significantly the reduction of the remaining α‐PbO 2 and decreases slightly the band‐gap energy of t‐PbO.