Hydroxyl Self-Trapping Strategy Enables Electrocatalysis at Ampere-Level Current Densities: Kinetics-Driven Lattice Oxygen Activation for Cl−-Rich Alkaline Water Electrooxidation

Abstract

The development of electrocatalysts that both work effectively at industrial current density and resist chloride ion (Cl⁻) corrosion remains a key challenge for hydrogen production from Cl^--rich alkaline water. Herein, we report a CrO_x-engineered nickel-based oxide catalyst (FeCoCrO_x/NF) that achieves exceptional activity and stability through a dual-functional interfacial mechanism. Combing in situ Raman spectroscopy, ¹⁸O isotopic labeling, and electrochemical analysis, we demonstrate that the oxygen evolution reaction follows a lattice oxygen-mediated mechanism. The CrO_x layer selectively adsorbs hydroxide ions, forming a dynamic interfacial barrier that electrostatically repels Cl⁻ ingress, thereby mitigating Cl^- corrosion. Through enthalpy-based analysis, we demonstrate that electronic redistribution via Cr–O–Fe bonding increases the vacancy formation energy of Fe, thereby suppressing its dissolution. In alkaline electrolyte containing 0.5 M Cl⁻ (1.0 M KOH), the catalyst is operating continuously for 1400 h at an industrial current density of 1000 mA cm⁻². Furthermore, the catalyst retains 99.5% of its initial activity under fluctuating current density (100–1000 mA cm⁻²), demonstrating robustness required for industrial electrolyzers. This study establishes a paradigm for designing corrosion-resistant electrocatalysts through the synergistic modulation of interfacial ion selectivity and bulk lattice oxygen activation, advancing the application of green hydrogen production in Cl⁻-rich alkaline water.