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‐H 2 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.