Preparation and evaluation of a multi-component catalyst by using a co-sputtering system for anodic oxidation of ethanol

In this study, a remarkable promotion of ethanol electrooxidation by a Pt–Ru–W alloy is reported for an improvement of the anodic reaction of a direct ethanol fuel cell (DEFC). Pt-based binary and ternary electrocatalysts including Pt–Ru–W deposited onto a Au substrate were prepared by co-sputtering process. By using this process, several metals can be arranged simultaneously and uniformly. The catalysts deposited onto Au were evaluated for anodic electrode in 1 mol dm−3 ethanol + 0.5 mol dm−3 sulfuric acid by electrochemical measurements. The performance of Pt–Ru–W was desirable in comparison to that of binary alloys, such as Pt–W, Pt–Sn and Pt–Ru, which exhibit higher catalytic activity than single Pt metal layer electrode. Ethanol electrooxidation on Pt–Ru–W alloy showed a cathodic shift in the onset potential and a higher current density than the binary alloy electrodes. It was found that Pt–Ru–W ternary catalyst effects to not only methanol oxidation reaction but also ethanol oxidation reaction and that the current density of ethanol oxidation with Pt–Ru–W is about 2/3 to that of methanol at 0.5 V versus Ag/AgCl. The onset potentials for the ethanol oxidation reaction matched well the anodic peak potentials of the background volutammograms, i.e., 0.15 V versus Ag/AgCl for Pt–Ru–W and 0.35 V versus Ag/AgCl for Pt–W and Pt–Ru electrodes. That is, it was postulated that the background peak current indicates the generation of oxide species like metalsingle bondOH necessary to complete the ethanol oxidation to CO2.