Palladium and palladium-copper alloy nano particles as superior catalyst for electrochemical oxidation of methanol for fuel cell applications

Monometallic Pd, Cu and bimetallic Pd98Cu2, Pd94Cu6, Pd86Cu14 alloy nano particles with small average particle diameter (6-10 nm) are synthesised by facile single pot hydrothermal reduction with hydrazine solution at 75 °C in absence of any special capping agent. Synthesized nano-materials are characterized by X-ray, electron diffraction, different microscopic and electro-analytical studies. Graphite supported bimetallic PdxCu100-x alloy unlike mixed nano particles show synergistic and enhanced electro catalytic activity towards oxidation of methanol in alkali. The maximum specific peak current of 987 mA mg−1 and equilibrium exchange current of 5 × 10−6 mA mg−1 of Pd obtained for Pd94Cu6 alloy in the present work are much better than the corresponding values reported for PdxCu100-x composite and alloy materials. Cyclic voltammograms of possible intermediates like formaldehyde as well as sodium formate and ex-situ FTIR and chromatographic studies of reaction products reveal that Cu accelerates formation of formate rather than carbonate elucidating the plausible mechanism of the reaction.