Large‐Scale Synthesis of Spinel Ni(x)Mn(3‐x)O(4) Solid Solution Immobilized with Iridium Single Atoms for Efficient Alkaline Seawater Electrolysis

Seawater electrolysis not only affords a promising approach to produce clean hydrogen fuel but also alleviates the bottleneck of freshwater feeds. Here, a novel strategy for large‐scale preparing spinel Ni(x)Mn(3‐x)O(4) solid solution immobilized with iridium single‐atoms (Ir‐SAs) is developed by the sol–gel method. Benefitting from the surface‐exposed Ir‐SAs, Ir(1)/Ni(1.6)Mn(1.4)O(4) reveals boosted oxygen evolution reaction (OER) performance, achieving overpotentials of 330 and 350 mV at current densities of 100 and 200 mA cm(–2) in alkaline seawater. Moreover, only a cell voltage of 1.50 V is required to reach 500 mA cm(–2) with assembled Ir(1)/Ni(1.6)Mn(1.4)O(4)‖Pt/C electrode pair under the industrial operating condition. The experimental characterizations and theoretical calculations highlight the effect of Ir‐SAs on improving the intrinsic OER activity and facilitating surface charge transfer kinetics, and evidence the energetically stabilized *OOH and the destabilized chloride ion adsorption in Ir(1)/Ni(1.6)Mn(1.4)O(4). This work demonstrates an effective method to produce efficient alkaline seawater electrocatalyst massively.