Enhanced Seawater Oxygen Evolution with Improved Electronic Environment of NiCoPS through Fluorine Doping

Developing economical and robust electrocatalysts to prevent chlorine ions corrosion and improve seawater splitting efficiency is essential for seawater electrolysis. Herein, fluorine-doped nickel cobalt phospho-sulfide nanowires (F-NiCoPS NWs) were synthesized as high-performance catalysts for overall seawater splitting. The strongly electronegative F anion is favorable to build weak metal fluorine bonds, which easily break to generate highly active species of Ni/Co-hydroxides/oxyhydroxides protective layer on the electrode surface. This process effectively avoids chlorine evolution reaction (ClER)-induced dissolution, and enhances the stability of catalysts. Density functional theory (DFT) calculations indicate that the electronegative fluorine affects the electronic structure of the catalyst’ surface, further enhancing the adsorption energy and electronic conductivity of the reaction intermediates. F-NiCoPS with appropriate F doping significantly decreased the overpotential (228 (303) mV at 10 (100) mA cm-2) and the Tafel slope (44 mV dec-1) in alkaline seawater, and exhibited a long stability of 100 h. This work provides new insights for constructing effective, cost-efficient and non-noble metal electrocatalyst for alkaline seawater splitting.