Lattice Cl⁻ reconstruction in a ternary hydroxychloride pre-electrocatalyst for efficient saline water oxidation

The development of efficient electrocatalysts for saline water oxidation (SWO) is imperative for advancing seawater splitting technology to produce green hydrogen. In this work, we report a NiFeCo hydroxychloride pre-electrocatalyst with the merits of high surface area and anti-corrosion, which exhibited both active and stable SWO performance. The lattice Cl⁻ of NiFeCo hydroxychloride was leached during catalysis, leading to the 35.4% enlarged surface area of the catalysts, which showed a SWO overpotential of 369 mV at 100 mA·cm⁻², which is 105 and 154 mV lower than that of the NiFeCo layered double hydroxide and commercial RuO₂ catalysts, respectively. Moreover, in-situ Raman demonstrated the incorporation of electrolyte Cl⁻ to the lattice of the catalysts and the re-formation of Co–Cl bonds, which resulted in the enhanced anti-corrosion performance and high electrocatalytic stability for 100 h. These results provide a convincing demonstration of the reconstruction of ternary hydroxychloride pre-electrocatalysts for efficient seawater splitting hydrogen production.