ABSTRACT Electrocatalytic seawater electrolysis remains challenging due to chloride‐induced corrosion and impaired reaction kinetics, particularly at high current densities. Herein, single iridium atoms anchored on Ni(OH) 2 are demonstrated as an electrocatalyst for seawater electrolysis, enabling stable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance during 500 h of continuous seawater electrolysis. Experimental and theoretical analyses reveal that Ir facilitates the formation of γ‐NiOOH and Ir─O species during OER, while Cl − stabilizes reactive intermediates and accelerates Ni oxidation. On the other hand, for HER, Ir sites facilitate water dissociation and stabilize H* intermediates, whereas Cl − ions modulate the adsorption–desorption equilibrium, enhancing HER kinetics without structural degradation. Moreover, it is found that Cl − increases the density of states near the Fermi level of Ni 3d and Ir 5d orbitals, lowers the energy barriers for *H, *OH, *O, and *OOH intermediates, and promotes charge transfer across Ir─O─Ni interfaces, which could be the reason for the addressed HER and OER activity. This work provides insights into the cooperative role of Ir and Cl − ions and establishes a pathway for the design of electrocatalysts for seawater splitting.
Feizpoor et al. (2026) studied this question.