Lewis acid-mediating local alkaline microenvironment for efficient oxygen evolution

Regulating the coordination environment of catalytic active sites is critical for improving the oxygen evolution reaction (OER) in alkaline media. In this work, a rational strategy based on hard-soft-acids-base principle is proposed to finely control the local environment around active sites by introducing hard Lewis-acid (W^{6 +}) sites. In situ characterizations indicate that the Lewis acid selectively captures hydroxide ions (which act as hard Lewis bases), thereby modifying the hydrogen-bonding network and establishing a stable, hydroxide-enriched layer near the active regions. This persistently alkaline interface inherently inhibits chemical degradation, particularly under high-current conditions. Computational studies verify that the hydroxyl capture promotes and secures the *OOH transition states on the catalyst surface, reducing the energy barrier of the rate-limiting step. The designed Ni₃Se₂ catalyst, incorporating Lewis acidic W⁶⁺ centers (Ni₃Se₂/NiWO₄), demonstrates outstanding catalytic activity in alkaline electrolyte, requiring only 235 mV overpotential to reach 10 mA cm⁻² and maintaining stable operation for over 500 h at 100 mA cm⁻². When incorporated within an anion exchange membrane water electrolyzer (AEMWE), the Ni₃Se₂/NiWO₄-based cell exhibits exceptional endurance, operating continuously for 96 h at an industrial-level current density of 1 A cm⁻². This study highlights Lewis acid-mediated active-site regulation as an effective strategy to control OER intermediates and enhance catalytic performance in alkaline water electrolysis.