Pyrenetetrasulfonic Acid Tetrasodium Salt‐Modified CoFe Layered Double Hydroxide Enables Stable Alkaline Seawater Oxidation

Abstract Seawater electrolysis is deemed a green and promising technology for producing hydrogen in coastal areas. Nevertheless, ample chloride ions (Cl^–) in seawater can corrode anode, especially at ampere‐level current densities (j), which represents a significant impediment to the seawater‐to‐H₂ system. In this study, we present a CoFe layered double hydroxide nanoneedle array modified with 1,3,6,8‐pyrenetetrasulfonic acid tetrasodium salt (PTS) on Ni foam (CoFe LDH@CoFe‐PTS/NF) as a highly efficient electrocatalyst for seawater oxidation. It reveals that PTS with a large negative charge density can effectively repel Cl^– and keep active sites working stably during alkaline seawater oxidation. Thus, CoFe LDH@CoFe‐PTS/NF demonstrates excellent OER performance and can achieve j of 500 and 1000 mA cm⁻² at low overpotentials (η) of 333 and 364 mV. Moreover, it maintains a stable and continuous electrolysis for 500 h with minimal amounts of active chlorine generation.