Fluorine-induced surface protection strategy for bifunctional high entropy electrocatalysts enables stable seawater splitting

Electrolysis of seawater for hydrogen production on large-scale has garnered great attention as a breakthrough technological leap. Developing efficiency and cost-effective electrocatalysts remains at the forefront of this field. However, the seawater electrolysis encounters challenges arising from metal deposition and chlorine chemistry. Herein, we unveil a fluorine doping strategy for FeCoNiCuZn high entropy materials, showcasing a performance of 1.56 V at 50 mA·cm^–2 with long-term durability exceeding 1000 h in alkaline seawater. Experimental and theoretical evidence proves that the improvement is ascribed to F incorporation strengthens Lewis acid sites, which can absorb OH^– to resist cation deposition and Cl^– attack. The synergy effect between F and metal species further optimizes the intermediate adsorption energies by tuning the electronic structure. Significantly, the general efficacy of this approach is exhibited in a series of transition metal based high entropy materials with similar enhancements, among them, the FeCoNiCuZnCr and FeCoNiCuCr electrocatalysts demonstrate an even better HER and OER performance, respectively. This systematic study presents an in-depth perspective for designing efficient, robust high entropy electrocatalysts with high corrosion resistance in alkaline seawater electrolysis.