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

Abstract

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 VO₄³⁻-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 VO₄³⁻-NiFe LDH/VO_x/NF undergoes in situ conversion to VO₄³⁻, combining with intercalated VO₄³⁻ to form a dynamically adaptive VO₄³⁻ 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.