Vacancy‐Engineered Interfacial Electrons Modulation in NiCo Hydroxide/MoS ₂ Heterostructures for Boosted OER Electrocatalysis

ABSTRACT Developing efficient and durable oxygen evolution reaction (OER) electrocatalysts is crucial for sustainable hydrogen production via water electrolysis. Herein, nickel‐cobalt hydroxide/molybdenum disulfide heterostructures (NiCo/MoS ₂ )with discriminatively engineered cationic (NiCo/Mo ^vac S ₂ ) and anionic (NiCo/MoS ^vac ₂ ) vacancies for orchestrating electron transfer were constructed to clarify their distinct roles in regulating interfacial electronic properties and OER performance. Experimental and theoretical analyses demonstrate that Mo vacancies significantly enhance interfacial electron transfer. This facilitates the OER kinetics by modulating the adsorption energy of *O intermediate and thereby shifting the potential‐determining step from the deprotonation step to the hydroxyl coupling step, which yields a low overpotential of 256 mV at 10 mA cm ⁻² and a small Tafel slope of 68.5 mV dec ⁻¹ . In contrast, S vacancies promote electron delocalization within MoS ₂ but exhibit inferior catalytic enhancement. The Mo‐vacancy‐modified NiCo/Mo ^vac S ₂ electrode holds practical application potential in alkaline electrolyzers, achieving 1 A cm ⁻² at 2.11 V (60°C) and operating stably for over 300 h. This work highlights the pivotal importance of vacancy type in heterointerfacial design and provides a strategic direction for developing advanced electrocatalysts.