Tungsten electrochemistry in alkaline solutions-Anodic dissolution and oxygen reduction reaction

Oxygen reduction reaction (ORR) was investigated in alkaline solution on tungsten electrode subjected to a previous anodic dissolution. The rotating disk cyclic voltammetry and rotating disc chronoamperometry were used. Both unsupported and potassium pechlorate and sulfate supported solutions were examined. The most striking feature of recorded ORR curves is the large difference of ORR overpotential during anodic and cathodic sweep. This was attributed to the formation of tungsten oxide on the surface. It was demonstrated that electrode pretreatment as well as the electrolyte composition greatly affects ORR electrochemistry on tungsten electrode, and the influence of sulfates is discussed