Effects of RuO₂ contents on characteristics of Ti/SnO₂+Sb₂O₃ /RuO₂+PbO₂ electrodes

The RuO₂+PbO₂ coatings deposited on a Ti/SnO₂+Sb₂O₃ have been prepared by the thermal decomposition of RuCl₃+Pb(NO₃)₂. The surface morphology and microstructure of the coating were investigated by scanning electron microscopy. The electrocatalytic activity of the anodes was assessed by polarization curves and voltammetric charge at 25°C and 1.0 mol/L in aqueous H₂SO₄. The results show that the current density on the Ti/SnO₂+Sb₂O₃ /RuO₂+PbO₂ electrodes increases at a constant electrode potential and the voltammetric charge also increases at a constant scanning rate with increasing the content of RuO₂, it means that the electrocatalytic activity of the electrodes rises when RuO₂ content increases. Accelerated life tests were performed at 60°C and 1.0 mol/L in aqueous H₂SO₄ with an anodic current of 2.0 A/cm². The experimental results show that the accelerated lifetime decreases with increasing RuO₂ content, but comparing with the electrodes without an intermediate layer, the accelerated lifetime of Ti/SnO₂+Sb₂O₃ /RuO₂+PbO₂ electrodes is prolonged obviously. The SEM analysis reveals that surfaces of the electrodes take on a variety of morphology with variation of the content of RuO₂, which probably affect the electrocatalytic activity and the lifetime of the anodes.