Strain Effect Triggers Pt Adaptive Mechanism to Construct Brønsted Acid Microenvironment for Ampere‐Level Hydrogen Production From Alkaline Seawater

Intermittent renewable energy‐driven seawater hydrogen production can alleviate freshwater resource pressure and is of great significance in future energy systems. However, the localized microenvironment changes at the cathode and the strong interactions between other impurities and the electrolyzer lead to performance degradation and reduced equipment lifespan. Here, we report an alkaline seawater cathode catalyst for hydrogen production in an anion exchange membrane water electrolyzer (AEMWE). This catalyst can dynamically adjust the local reaction environment on the cathode surface. Through the reversible changes in the oxidation state of Pt in high‐entropy intermetallic compounds, a Brønsted acid‐like environment is formed near the reaction interface, inhibiting the formation of precipitates. In situ characterization confirmed that this Brønsted acid‐like environment can promote hydrogen production from alkaline seawater. Using alkaline seawater electrolysis, AEMWE operated stably for over 2000 h at an industrial‐grade current density of 1.0 A cm −2 (1.74 V).