Corrosion resistance and electrocatalytic properties of Co–W alloy coatings

Abstract

Corrosion behaviour of Co–W coatings deposited on copper substrates was studied in 3·5 wt-% NaCl aqueous solution using polarisation technique. The physicochemical characterisation of the alloy coatings was studied by scanning electron microscopy and energy dispersive X-ray analysis techniques. The study revealed the extent of shift in corrosion potential towards the noble direction and the decrease in corrosion current density for Co–W coatings. Among the various Co–W coatings studied here, the Co_78·5W_21·5 coating presented the best corrosion behaviour and superior corrosion potential compared to pure cobalt coating. In addition, their catalytic activity towards methanol electro-oxidation in alkaline medium was assessed by cyclic voltammetry technique. In cyclic voltammetry studies, Co–21·5 wt-%W electrode shows a significantly higher response for methanol oxidation than pure cobalt electrode.