The effect of composition of Ni-supported Pt-Ru binary anode catalysts on ethanol oxidation for fuel cells

The effect of the composition of a platinum-ruthenium (Pt-Ru) binary catalyst on a Ni-support for the anodic oxidation of ethanol in aqueous alkaline media has been studied. Co-deposition of nano-crystallites of a Pt-Ru electrocatalyst of varying composition, has been made on Ni-supports by galvanostatic deposition from precursor salt solutions of suitable composition, without using any capping agent. Conjugated scanning electron microscopic-energy dispersion X-ray spectroscopic studies reveal slight alteration of the atomic composition of the electrocatalyst on the electrode surface to that in the deposition bath, as expected. The excellent electrocatalytic activities of the electrodes for the anodic oxidation of ethanol have been found to depend on the mutual variation of composition of the binary catalyst. From cyclic voltammetric, chronopotentiometric, steady state polarization and electrochemical ac impedance studies, it can be inferred that the best catalytic activity of a Pt-Ru binary electrocatalyst on a Ni-support for anodic oxidation of ethanol contains 32–47 at.% of Ru. Moreover, the composition for the best activity within the said range is tilted towards more at.% of Ru when high current density is drawn whereas the composition containing a lower at.% of Ru is favoured when the current density drawn is relatively low.