High‐Performance Alkaline Seawater Electrolysis with Anomalous Chloride Promoted Oxygen Evolution Reaction

Abstract A highly selective and durable oxygen evolution reaction (OER) electrocatalyst is the bottleneck for direct seawater splitting because of side reactions primarily caused by chloride ions (Cl − ). Most studies about OER catalysts in seawater focus on the repulsion of the Cl − to reduce its negative effects. Herein, we demonstrate that the absorption of Cl − on the specific site of a popular OER electrocatalyst, nickel‐iron layered double hydroxide (NiFe LDH), does not have a significant negative impact; rather, it is beneficial for its activity and stability enhancement in natural seawater. A set of in situ characterization techniques reveals that the adsorption of Cl − on the desired Fe site suppresses Fe leaching, and creates more OER‐active Ni sites, improving the catalyst's long‐term stability and activity simultaneously. Therefore, we achieve direct alkaline seawater electrolysis for the very first time on a commercial‐scale alkaline electrolyser (AE, 120 cm 2 electrode area) using the NiFe LDH anode. The new alkaline seawater electrolyser exhibits a reduction in electricity consumption by 20.7 % compared to the alkaline purified water‐based AE using commercial Ni catalyst, achieving excellent durability for 100 h at 200 mA cm −2 .