Anionic formulation of electrolyte additive towards stable electrocatalytic oxygen evolution in seawater splitting

Hydrogen generation through seawater electrolysis provides a promising, attractive pathway towards the utilization of sustainable energy. However, the catalytic activity and stability of oxygen evolution anode are severely limited by the chloride-induced corrosion and competitive oxidation reactions. In this work, we demonstrate an anion-assisted performance improvement strategy by quick and universal screening of electrolyte additive via correlating Cl − repellency with the anionic properties. Particularly, the addition of phosphate ions is found to enable highly stable alkaline seawater splitting at industry-level current density (0.5 A cm −2 ) over 500 h using transition metal hydroxides as anodic electrocatalysts. In situ experiments and theoretical simulations further reveal that the dynamic anti-corrosion behaviors of surface-adsorbed phosphate ions are attributed to three factors including repelling Cl − ions without significantly blocking OH − diffusion, preventing transition metal dissolution and acting as a local pH buffer to compensate the fast OH − consumption under high current electrolysis.