Abstract: Pd micropartieles modified by polyaniline (PAN (Pd)) which was obtained by using H₆P₄O₁₃ as supporting electrolyte exhibited a considerably higher catalytic activity in oxidation of formic acid than the bare Pd electrode. Incorporation of Pd microparticles in PAN films were made by potential cycling between-0.2V and 0.5V(υ s. SCE) in 0.01mol/L PdCl₄^2- in about 15 Min. The catalytic activity was found in dependence on the size of the Pd particles, affected by the morphology of PAN film used. The XPS and electrochemical results reveal that the electrocatalytie mechanisms are different at the PAN(Pd) and bare Pd electrodes.

Key words: formic acid, oxidation, elecrtocatalysis, polyaniline, Pd microparticle