Electron Islands‐Induced Interface Engineering in FeP@NiCoP/Mo ₄ P ₃ for Efficient Hydrogen Evolution Catalysis

Abstract This study employs an “electron island” micro‐interface engineering strategy to construct a NiCoP/Mo ₄ P ₃ heterostructured catalytic system on a FeP substrate via a synergistic hydrothermal synthesis and low‐temperature phosphorization approach. The unique open hierarchical architecture provides atomic‐scale anchoring sites for small‐sized Mo ₄ P ₃ quantum dots (QDs), forming a high‐density “electron island‐substrate” micro‐interface network, which drastically increases the population of active micro‐interface sites between the two phases. Concurrently, the discretely distributed QDs induce interfacial charge polarization through quantum confinement effects, generating a robust built‐in electric field at the heterointerfaces that drives directional electron migration. Density functional theory (DFT) calculation shows the interfacial interaction between NiCoP and Mo ₄ P ₃ can effectively manipulate the electronic architecture and regulate the H* adsorption energy, further decreasing the Gibbs free energy (ΔG _H* ). FeP@NiCoP/Mo ₄ P ₃ can make full use of the active sites generated at the interface, to give full play to the catalytic properties of heterogeneous structures, which ensures the significantly enhanced hydrogen evolution reaction (HER) catalytic efficiency and excellent long‐term stability in alkaline water and complicated seawater environments. This work provides guidance and direction to maximize the interface effect for designing efficient and stable catalysts.