Interfacial Engineering of MoP ₂ –NiCoP Heterostructures for Enhanced Alkaline Water Splitting: A Density Functional Theory Investigation

The outstanding alkaline hydrogen evolution reaction (HER) performance of MoP 2 –NiCoP heterostructure has been reported. However, the mechanism behind its catalytic activity remains unclear, and the underlying synergistic catalysis has not been revealed at the atomic scale. Based on these research gaps, the theoretical investigation on the MoP 2 –NiCoP heterostructure is conducted, revealing that the MoP 2 –NiCoP heterostructure exhibits superior HER activity ( = −0.016 eV) but limited oxygen evolution reaction (OER) performance ( = 2.589 eV). Electronic structure analysis demonstrates that interfacial charge redistribution optimizes the adsorption strength of the H* intermediate, significantly lowering the HER energy barrier while restricting the O* → OOH* transition, thus hindering OER processes. Doping strategies (e.g., W, Ta) further enhance HER performance and a linear scaling relationship between the d ‐band center () and HER activity descriptor () shows strong correlation ( R 2 = 0.993). This work reveals the origin of the high intrinsic HER activity and the interfacial synergistic mechanism in the MoP 2 –NiCoP catalyst, verifying its lack of effective OER activity. It further identifies a novel strategy for directional enhancement of catalytic performance through electronic structure modulation, establishing a theoretical framework for designing bifunctional electrocatalysts on experiments.