Unraveling the composition-activity relationship of Pt-Ru binary alloy for hydrogen oxidation reaction in alkaline media

The research and development of hydrogen oxidation reaction catalysts in alkaline media is a prerequisite for the commercialization of alkaline polymer electrolyte fuel cell. Pt-Ru bimetallic catalyst was found to be more active towards HOR than Pt in alkaline, but the composition-activity relationship of Pt-Ru alloys is still lacking. Herein, a series of Pt-Ru alloy planar electrodes with 14 different compositions were prepared in a high throughput fashion using an improved magnetron sputtering method. The atomic ratio of Pt was controlled from 6.7% to 99.7% within the samples. The corresponding electro-catalytic activities towards the HOR in alkaline were systematically measured by rotating disc electrode method. A volcano-shape relationship between the HOR exchange current density and the Ru atomic fraction was revealed, and maximum activity was observed at ca. 55% content of Ru. The enhancement in electro-catalytic activity is attributed to a reduction in the electronic charge density of Pt upon Ru doping.