Boosting Hydrogen Evolution Reaction via Electronic Coupling of Cerium Phosphate with Molybdenum Phosphide Nanobelts.

Abstract

Molybdenum phosphide (MoP) is regarded as one of the most promising alternatives to noble-metal based electrocatalysts for efficient hydrogen evolution reaction (HER) due to its similar d-band electronic structure to noble metals and tunable features associated with phase and composition. However, it still remains a great challenge to construct MoP electrocatalysts with abundant active sites that possess ideal H binding strength to promote catalytic performance. In this work, it is found that by anchoring a rare earth compound, cerium phosphate (CePO4 ) on MoP (CePO4 /MoP), the stabilized Ce3+ in CePO4 can significantly boost the formation of oxygen vacancies in ceria (CeO2 ) in situ formed on CePO4 surface during HER, which effectively regulates the d-band electronic density-of-states of MoP, increases the numbers of active sites, and promotes the vectorial electron transfer, therefore greatly enhancing the HER performance of MoP. The optimized CePO4 /MoP/carbon cloth (CC) electrocatalyst exhibits a significantly improved HER performance with an overpotential of 48 mV at 10 mA cm-2 and a Tafel slope of 38 mV dec-1 , about two times better than the HER performance of MoP catalyst without CePO4 (with an overpotential >80 mV dec-1 at 10 mA cm-2 ), very close to commercial Pt/C catalyst.