Interlayer Water Activation Supplemented Dual Oxygen Evolution Reaction Channels in Layered Double Hydroxides for Efficient Seawater Electrolysis

Direct seawater electrolysis powered by renewable electricity offers a promising avenue for sustainable production of green hydrogen, yet the challenges of chloride‐induced corrosion and sluggish kinetics of oxygen evolution reaction (OER) persist with electrocatalysts. Here, a sulfur‐modified CoFe‐layered double hydroxide catalyst (S‐CF· n H 2 O) is developed to address the above activity and stability issues, in which sulfur etching‐assisted targeted reconstruction occurs and yields high‐density accessible active sites both on the surface and in the interlayer galleries; meanwhile, sulfate ions derived from sulfur oxidation adsorb on catalyst and create an electrostatic Cl − ‐repelling barrier. Featuring interlayer space as a supplementary reaction region and an electrostatic‐protecting sulfate layer, S‐CF· n H 2 O catalyst achieves exceptional OER activity (with an overpotential of 370 mV at 1 A cm −2 ) and unprecedented durability exceeding 12 000 h in alkaline seawater; the seawater electrolyzer assembled from S‐CF· n H 2 O also demonstrates stable operation for 10 000 h at 600 mA cm −2 . In situ spectroscopic and isotope tracing analyses reveal a distinct oxide pathway mechanism with the interlayer water, in contrast to the adsorbate evolution mechanism occurring at the catalyst outer surface. This work conceptually reveals the robustness of interlayer chemistry for the design of high‐performance LDH‐based catalysts.