Autonomous Interface Stabilization via Ni Doping, Sulfur Vacancy Regulation, and Carbon Encapsulation for Durable Hydrogen Evolution in Acidic Media.

Designing HER catalysts that autonomously adapt to acidic environments remains a critical challenge for scalable hydrogen production. Here, a multifunctional, self-stabilizing electrocatalyst-C@Cd₀.₉Ni₀.₁S-featuring a dynamically responsive Ni-S vacancy interface embedded in a conductive carbon matrix is presented. Ni doping induces local electron accumulation and facilitates sulfur vacancy formation, thereby reprogramming the electronic structure to lower the hydrogen adsorption free energy (ΔG) and promote hydrogen spillover. Sulfur vacancies enhance charge redistribution and proton binding, while carbon encapsulation ensures charge continuity and structural durability under acidic stress. The catalyst achieves a low overpotential of -0.24 V at 100 mA cm for 10 days and maintains stable operation at 500 mA cm without metal leaching. DFT and operando XPS analyses confirm that the Ni-S vacancy interface adaptively modulates electronic structure and interfacial reactivity, enabling intelligent surface response during HER. This work establishes a rational design framework for acid-stable, precious-metal-free HER catalysts with autonomous interface regulation.