High efficient electrocatalytic oxidation of methanol on Pt/polyindoles composite catalysts

Novel composite catalysts have been fabricated by the electrodeposition of Pt onto the glassy carbon electrode (GC) modified respectively with polyindole (PIn) and poly(5-methoxyindole) (PMI) and used for the electrooxidation of methanol in acid solution of 0.5 M H2SO4 containing 1.0 M methanol. As-formed composite catalysts are characterized by SEM, XRD and the electrochemical methods. The results of the catalytic activity for methanol oxidation show that the two composite catalysts exhibit higher catalytic activity and stronger poisoning-tolerance than Pt/polypyrrole/GC (Pt/PPy/GC) and Pt/GC. Electrochemical impedance spectroscopy indicates that the methanol electrooxidation on the composite catalysts at various potentials shows different impedance behaviors. At the same time, the charge-transfer resistance for electrooxidation of methanol on Pt/PIn/GC and Pt/PMI/GC is smaller than those on Pt/PPy/GC and Pt/GC. The present study shows a promising choice of Pt/PIn and Pt/PMI as composite catalysts for methanol electrooxidation.