Electronic Structure Modulation of Ni ₂ P Nanospheres via Interfacial Control With Lattice‐Expanded MoS ₂ Nanosheets for Enhanced Hydrogen Evolution

The development of cost‐effective and durable electrocatalysts is a prerequisite for scalable hydrogen production via water electrolysis. In this context, modulating the electronic structure of transition‐metal phosphide electrocatalysts via interfacial engineering with transition‐metal chalcogenides has emerged as a compelling strategy to accelerate the hydrogen evolution reaction. Herein, we report an ultrasonication‐assisted synthesis of ultrathin sub‐20‐nm MoS 2 intimately integrated with Ni 2 P nanoparticles (R‐MoS 2 @Ni 2 P). In R‐MoS 2 @Ni 2 P, the unique heterointerface configuration induces a bending‐induced lattice expansion in ultrathin MoS 2 and modulates the electronic structure of Ni 2 P, facilitating interfacial charge redistribution for efficient HER. XPS analysis reveals that electrons are partially transferred from Ni 2 P to ultrathin MoS 2 . Furthermore, density functional theory calculations revealed that tensile strain in the O‐MoS 2 results in a downshift of the d‐band center and an optimized hydrogen adsorption free energy (∆G H* ). Consequently, the as‐prepared R‐MoS 2 @Ni 2 P exhibits significantly enhanced HER activity and long‐term stability in both half‐cell measurements and a PEMWE system compared with pristine Ni 2 P. This study demonstrates that interfacial engineering with ultrathin MoS 2 nanosheets is an effective strategy to optimize the electronic properties of active Ni 2 P species, offering a promising design framework for advanced energy‐conversion catalysts.