In Situ Construction of Built-In Opposite Electric Field Balanced Surface Adsorption for Hydrogen Evolution Reaction

Achieving a balance between H-atom adsorption and binding with H₂ desorption is crucial for catalyzing hydrogen evolution reaction (HER). In this study, the feasibility of designing and implementing built-in opposite electric fields (OEF) is demonstrated to enable optimal H atom adsorption and H₂ desorption using the Ni₃(BO₃)₂/Ni₅P₄ heterostructure as an example. Through density functional theory calculations of planar averaged potentials, it shows that opposite combinations of inward and outward electric fields can be achieved at the interface of Ni₃(BO₃)₂/Ni₅P₄, leading to the optimization of the H adsorption free energy (ΔG_H*) near electric neutrality (0.05 eV). Based on this OEF concept, the study experimentally validated the Ni₃(BO₃)₂/Ni₅P₄ system electrochemically forming Ni₃(BO₃)₂ through cyclic voltammetry scanning of B-doped Ni₅P₄. The surface of Ni₃(BO₃)₂ undergoes reconstruction, as characterized by Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) and in situ Raman spectroscopy. The resulting catalyst exhibits excellent HER activity in alkaline media, with a low overpotential of 33 mV at 10 mA cm^-2 and stability maintained for over 360 h. Therefore, the design strategy of build-in opposite electric field enables the development of high-performance HER catalysts and presents a promising approach for electrocatalyst advancement.