Suppressing oxygen-vacancy-mediated chlorine corrosion for high-current stable seawater electrolysis

NiFe layered double hydroxide (NiFe LDH) is an efficient seawater oxygen evolution reaction (OER) catalyst. However, its long-term stability is severely limited by Cl^--induced corrosion. To address this issue, an innovative vanadate modification strategy is developed to mitigate Cl^- corrosion in NiFe LDH. The resulting VO₄ ^3--NiFe LDH/VO _x /NF catalyst exhibits excellent activity and durability in alkaline seawater, maintaining a current density of 1000 mA cm^-2 for 3500 h, which is significantly longer than the 300 h achieved by the single NiFe LDH. Through in situ characterization and theoretical studies, it is revealed that on the NiFe LDH, Cl^- preferentially adsorbs onto oxygen vacancies (O_v) generated via the lattice oxygen mechanism. This adsorption induces M-Cl coordination and further accelerates the formation of O_v, thereby driving a self-reinforcing corrosion cycle. By contrast, the VO _x on the surface of VO₄ ^3--NiFe LDH/VO _x /NF undergoes in situ conversion to VO₄ ^3-, combining with intercalated VO₄ ^3- to form a dynamically adaptive VO₄ ^3- species. These species generate a strong electrostatic field that repels Cl^-, while simultaneously stabilizing OH^- through a hydrogen-bonding network. As a result, it effectively suppresses metal-Cl coordination and optimizes the adsorption behavior of OH^-, thereby sustaining high catalytic activity and stability.