In‐situ Generation of Hydroxyl Layers in CoO@FeSe2 Catalyst for High Selectivity Seawater Electrolysis

Comprehensive Summary Seawater electrolysis holds great promise for hydrogen production in the future, while the development of anodic catalysts has been severely hampered by the side‐reaction, chloride evolution reaction. In this work, nano‐flower‐cluster structured CoO@FeSe 2 /CF catalysts are synthesized via a scalable electrodeposition technique, and the performance is systematically studied. The oxygen evolution reaction (OER) overpotential of CoO@FeSe 2 /CF is 267 mV at 100 mA·cm −2 , which is significantly lower than that of the IrO 2 catalyst (435 mV). Additionally, the catalyst shows high selectivity for OER (97.9%) and almost no loss of activity after a durability test for 1100 h. The impressive performance is attributed to the dense rod‐like structure with abundant active centers after electrochemical activation and the in‐situ generated CoOOH and FeOOH that improve the catalytic activity of the catalyst. The synergistic effect induced by the non‐uniform structure endows the catalyst with excellent stability.