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/VOx/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 (Ov) generated via the lattice oxygen mechanism. This adsorption induces M–Cl coordination and further accelerates the formation of Ov, thereby driving a self-reinforcing corrosion cycle. By contrast, the VOx on the surface of VO43−-NiFe LDH/VOx/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.