Pre‐Leached Sacrificial Heterojunction Enables Sustaining Industrial‐Grade Water Electrolysis

ABSTRACT Water electrolysis represents a promising approach for producing green hydrogen fuel from abundant renewable energy sources, offering a viable solution to reduce global reliance on fossil fuels. However, the leaching of active species from catalysts due to dynamic reconstruction poses significant durability challenges, limiting practical applications despite advances in catalytic activity. Herein, we introduce an innovative and versatile design featuring an inactive pre‐leaching region within the pre‐catalyst to decouple coordination anion substitution from active metal oxidation, thereby mitigating catalyst reconstruction. We fabricate a MoO 2 /Ni x S y system, utilizing readily oxidizable MoO 2 as a sacrificial component. This design effectively isolates the coordination anion substitution (S x− →OH − →O 2− ) around nickel sites from the oxidative transformation of nickel atoms in Ni x S y . Consequently, the MoO 2 /Ni x S y system evolves into a dual oxyanion co‐adsorbed NiOOH, marked by low structural disorder and strong Ni─O bonds for the oxygen evolution reaction (OER). This synergistic co‐adsorption enhances electron transfer, yielding an impressive overpotential of 253 mV at 1000 mA cm −2 and exceptional stability over 300 h. Scaled for industrial water electrolyzers, MoO 2 /Ni x S y maintains stable operation at 8000 mA for 360 h, achieving a record‐low voltage of 1.70 V, corresponding to energy consumption of 4.07 kWh m −3 H 2 .