Ethylene-Glycol Ligand Environment Facilitates Highly Efficient Hydrogen Evolution of Pt/CoP through Proton Concentrating and Hydrogen Spillover
Low catalytic kinetics of many non-precious electrocatalysts for hydrogen evolution reaction is often associated with their adverse hydrogen adsorption/desorption kinetics. Thus, improving their kinetics and understanding the mechanism is critically important. Herein, the strategy of utilizing unique ethylene glycol ligand environments is employed to circumvent the aforesaid kinetic limitations in the composites of Pt-loaded-CoP linked by ethylene-glycol through proton concentrating and hydrogen spillover. At a low Pt-loading of 1.5 wt.%, the catalytic performance is significantly improved with the dramatically decreased Tafel slopes from 104.6 mV/dec of CoP to 42.5 mV/dec. Control experiments and theoretical calculations reveal that ethylene-glycol concentrates hydrogen intermediates on Pt (>7.3 times), facilitates hydrogen spillover from hydrogen-enriched Pt to hydrogen-deficient CoP and modulates the local electronic structures to bring the thermo-neutral Pt/CoP interfacial sites, and improves the catalytic kinetics ultimately. The composites with 1.5 wt.% Pt-loading deliver a low overpotential of 21 mV at 10 mA/cm2 as well as a record high noble-metal utilization activity, outerperforming the commercial Pt/C and other hydrogen spillover electrocatalysts for HER. Such a strategy may provide insights for design of electrocatalysts.