Corrosion resistance of tetraborate anion intercalated reinforced cobalt-iron layered double hydroxides in alkaline perchlorine water splitting

Electrolytic seawater splitting is a crucial technical direction for hydrogen energy development. However, electrode corrosion induced by high-concentration chloride (Cl − ) remains a key bottleneck restricting its large-scale application. Though cobalt‑iron layered double hydroxide (CoFe-LDH) has good intrinsic catalytic activity, it is susceptible to Cl − corrosion, leading to degraded catalytic performance. Herein, this study proposes a research strategy for synthesizing tetraborate ion (B 4 O 7 2− ) intercalation and regulated CoFe-LDH (CoFe-BLDH) via a one-step hydrothermal method. Via DFT calculation, In-situ Raman spectroscopy, and other characterization techniques, it was verified that the intercalation of cyclic B 4 O 7 2− not only endows the catalyst with excellent hydrophilicity, promotes the generation of high-valent active species and regulates electron transfer, but also effectively inhibits the competitive adsorption of Cl − through a unique charge repulsion effect. In an alkaline high-chloride environment (1.0 M KOH + 2.0 M NaCl), this material exhibits remarkable catalytic activity with dual functional properties: oxygen evolution reaction (OER): 284 mV@100 mA cm −2 ; hydrogen evolution reaction (HER): 179 mV@10 mA cm −2 , representing activity improvements of approximately 21.6% and 11.8%. The overall water splitting constructed with CoFe-BLDH delivers a current flux of 100 mA cm −2 at a working voltage of only 1.820  V in a harsh high-chloride system and can exhibit stable performance for more than 100 h. This study provides practical theoretical guidance for improving the performance of layered double hydroxides in high-chloride media.