Deciphering promotion of MoP over MoC in Pt catalysts for methanol-assisted water splitting reaction.

Molybdenum-based compounds show promising promotion effects on Pt catalysts for energy-relevant catalysis reactions. Herein, a more effective promotion effect of MoP than MoC was found in assisting Pt nanoparticles for methanol-assisted hydrogen generation in light of the strong metal-support interaction and synergistic effect between Pt and MoP/C nanospheres. Electrochemical analyses and theoretical calculations demonstrated that Pt-MoP/C facilitated the oxidation and removal of CO intermediates more effectively than Pt-MoC/C. This enhanced performance was attributed to the distinct 6-coordination environment of hexagonal MoP and the elevated electron density of Mo induced by phosphorus. These structural and electronic features significantly enhanced electron transfer to Pt, thereby creating strong metal-support interaction and synergistic effect to improve the overall catalytic efficiency. Especially, the unique activities of Mo and Mo in the MoP modified the surface structure of Pt, lowered the Pt d-band center, and optimized the local chemical state of Pt atoms, which resulted in more optimized adsorption energy and charge transfer capabilities of intermediates. The Pt-MoP/C electrolyzer thus showed both lower cell voltage than that of Pt-MoC/C and Pt/C electrolyzers in water splitting and methanol-assisted water splitting for hydrogen generation. This study offers insightful information about the promotion effect of molybdenum-based compounds in Pt catalyst systems in energy-relevant catalysis reactions.