Microstructure, surface and electrochemical studies of electroless Cr-P coatings tailored for the methanol oxidative fuel cell

Cr-P is a new material of great importance as a decorative coating with nickel in automobile industries. Electroless plating of Cr-P alloy has been carried out using a suitable plating bath solution and working conditions. The deposit is characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray diffraction, X-ray photoelectron spectroscopy and polarization techniques. New phases appear on heat treatment of the coating. The composition (Cr/P) of the coating and the oxidation states of alloying elements vary from the surface to the bulk of the material. The coatings acted as a novel electrode material with good electrocatalytic activity (low overvoltage) and good corrosion resistance for anodic oxidation of methanol in H 2SO4 at normal working temperature. The good corrosion resistance of the Cr-P film is accounted for by the existence of a double oxyhydroxide passive film on the surface. The electrocatalytic activity of Cr-P is very high when compared with chromium alone. © Springer-Verlag 2005