Constructing a Highly Active Amorphous WO₃/Crystalline CoP Interface for Enhanced Hydrogen Evolution at Different pH Values

Hydrogen evolution through electrolysis of water is an effective approach to the current energy shortage, attracting extensive research attention. Herein, we constructed an amorphous WO₃/crystalline CoP (WO₃/CoP) heterostructure electrocatalyst by a facile two-step hydrothermal method followed by low-temperature phosphatization. Results of the electrocatalytic performance test revealed that WO₃/CoP displays extraordinarily robust stability and efficient hydrogen evolution reaction (HER) activity, which only needs overpotentials of 49 and 69 mV to deliver a current density of 10 mA cm^–2 in alkaline and acid medium, respectively. Further studies confirmed that amorphous WO₃ is wrapped around crystalline CoP and the rich amorphous–crystalline heterojunction interfaces directly optimized the adsorption energy of the intermediate by the downshift of P 2p and upshift of Co 2p orbits. Moreover, the interface between the amorphous WO₃ and crystalline CoP is essential to boost the reaction kinetics because the amorphous phase with many unsaturated bonds directly facilitates the adsorption of reactants and crystalline CoP with superior conductivity accelerates the transfer of electrons. This study provides a facile and feasible approach for constructing a crystalline/amorphous heterojunction catalyst for hydrogen generation.