Stable Bimetallene Hydride Boosts Anodic CO Tolerance of Fuel Cells

Active and durable anode electrocatalysts are of vital importance for practical implementation of fuel cells. However, the surface-adsorbed reaction intermediates, especially CO, easily poison and deactivate the electrocatalysts. Here, we report ultrathin molybdenum–palladium hydride (MoPdH) bimetallene as a high-efficiency electrocatalyst for the methanol oxidation reaction. This exhibits a 6.0-fold enhancement of mass activity relative to commercial Pd black catalyst. Alloying with Mo strongly enhances the H binding ability of Pd and thereby stabilizes the MoPdH bimetallene. The resulting ultrathin hydride structure and the stabilization of it by Mo alloying yields a MoPdH bimetallene with the outstanding CO tolerance. The stabilization is understood in terms of the Miedema rule, which thus provides a new opportunity for catalyst design boosting the commercialization of fuel cells based on stable bimetallene hydride nanosheets.