Regulative electronic redistribution of CoTe2/CoP heterointerfaces for accelerating water splitting

The interfacial synergy effect caused by the space charge transfer of heterojunctions can effectively modify the catalytic activity. Herein, a composite heterojunction catalyst of CoTe2/CoP with moderate Gibbs free energy of hydrogen adsorption is designed based on interfacial effects driven by work function difference between CoTe2 and CoP. As expected, CoTe2/CoP only needs overpotentials of 80 mV at 10 mA cm−2 and stability for continuous catalysis at the current density of 100 mA cm−2 for 20 h in hydrogen evolution reaction (HER). The experimental results and theory calculations identify that the built-in field drives the transfer of electrons from CoTe2 to CoP at the interface, which realizes electronic redistribution with increased electron density on the Co atoms in CoP and optimizes the adsorption-free energy of the reaction intermediates, thereby, accelerating HER kinetics. Besides, the CoTe2/CoP heterostructure also behaves the excellent catalytic activity towards water splitting.