Alleviating the Work Function of Vein-Like Co_XP by Cr Doping for Enhanced Seawater Electrolysis

For mass production of hydrogen fuel by electrochemical water splitting, seawater is preferred because of its abundant reserves on Earth. However, the current seawater electrolysis technology is seriously hindered by the low selectivity and poor stability of oxygen evolution reaction (OER) at anode due to undesirable chloride electrochemistry and severe corrosion in practical application. Herein, based on the “work function optimization” concept, vein-like Cr-doping Co_xP is rationally designed as a highly-efficient OER electrocatalyst for direct seawater electrolysis, achieving current densities of 20 and 100 mA cm^–2 at overpotentials of 268 and 325 mV, respectively, together with high OER selectivity and long-term stability. Experimental data and theoretical calculations reveal that the regulation of the electronic structure of Co_xP induced by Cr doping strongly alleviates the work function of Co_xP, which not only accelerates the electron transfer between the catalyst surface and the absorbates but also lowers the energy barriers of water dissociation and rate-determining step for both OER and hydrogen evolution reaction (HER). Moreover, Cr doping also protects the Co sites with robust valence states to maintain their high performance during the OER process, providing a new avenue to design non-noble metal-based catalysts for hydrogen generation from seawater electrolysis.