Trimetallic RuAuMo Thin-film Electrocatalyst Synthesized via Co-sputtering for Proton Exchange Membrane Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) is recognized as a promising technology for producing green hydrogen without emitting pollutants. However, the high cost and scarcity of platinum as a catalyst for hydrogen evolution reaction (HER) have hindered the commercialization of PEMWE, and the alternatives to platinum have been considerably studied. In this study, trimetallic RuAuMo-based thin-film HER electrocatalysts prepared via facile co-sputtering were investigated as HER electrocatalysts. The atomic composition of the RuAuMo electrocatalyst can be easily modulated by controlling the sputtering power of each target, and the activity of RuAuMo varies with the sputtering power of Au and Mo targets. Trimetallic RuAuMo electrocatalyst with the optimum atomic composition exhibits an overpotential of 50.4 mV at a current density of –10 mA/cm2 (η10) for HER, and it outperforms monometallic Ru (84.5 mV) and bimetallic RuAu (67.7 mV) electrocatalysts. This was attributed to the strong interactions between three elements, as revealed in XRD and XPS analyses. RuAuMo thin-film deposited on porous metallic support is directly used as a cathode for PEMWE, exhibiting a high PEMWE performance with a current density of 1.39 A/cm2 at a cell voltage of 1.8 V. These results demonstrate that RuAuMo thin-film is an active HER catalyst and suggest that sputtering is an effective method for the electrode fabrication of PEMWEs.