Intensified Accumulation of OH ⁻ and Improved Electron Transfer by Reactive Chlorine‐Resistant Layer Achieve High‐Durability Seawater Electrolysis

Abstract

ABSTRACT The stability and efficiency of direct seawater electrolysis are constrained by competitive Cl − adsorption and corresponding chlorine oxidation reaction, which further restricts diffusion and accumulation of OH − , as well as transfer of electrons involved in counterpart oxygen evolution reaction (OER), leading to severe Cl − ‐corrosion. Herein, intensified popular‐OH − accumulation and electron transfer are achieved through Ag‐mediated reactive chlorine‐resistant AgCl layer integrated onto NiCo‐oxyhydroxide (AgCl/NiCo‐OOH). Specifically, under external electric field driving, Ag species on the NiCo‐OOH surface undergo electrochemical transformation and free Cl − ‐immobilization via in situ formation of robust AgCl layer, subsequently leveraging common‐ion repulsion effect to sieve and control composition of ions in Stern layer, and thereby preventing Cl − corrosion. Simultaneously, the AgCl with high‐curvature induces electric fields across scales, incorporating mesoscale proximal‐tip and microscale built‐in electric fields, which significantly accelerates OER kinetics by intensifying diffusion and accumulation of reactant OH − and transfer of electron. Resultantly, the AgCl/NiCo‐OOH achieves an ultralow overpotential of 331 mV in alkaline simulated seawater and sustains stable operation for over 2200 h at Ampere‐level current density in alkaline seawater without Cl − ‐related corrosion. Further, the corresponding anion‐exchange membrane electrolyzer demonstrates a low energy consumption (4.50 kWh m −3 H 2 ) and long‐term durability (over 1500 h) at 500 mA cm −2 .