Rerouting Oxygen Evolution Through Interfacial Carbonate Chemistry in Near-Neutral Seawater Electrolysis

Near-neutral seawater electrolysis offers a sustainable and safe route for green hydrogen production, yet its development is constrained by a lack of fundamental understanding of the underlying reaction processes through various reaction paths. This study employs an integrated framework of electrochemical hydrodynamics and mesoscopic simulations, incorporating multicomponent mass transport, homogeneous reaction kinetics, and electron transfer, to decipher a possible role of carbonate species in the oxygen evolution reaction (OER) towards near-neutral seawater electrolysis. Our results suggest a plausible shift in the reaction paradigm: interfacial carbonate species could act as pivotal proton acceptors, while water molecules as oxygen donors. This suggests a distinct, favourable carbonate-mediated path that diverges from the conventional, sluggish H₂O path for the OER. In addition, based on simulations using model seawater electrolytes, as compared to the mass-transport-limited OH^- path, this plausible carbonate-mediated path can be predicted to enhance oxygen production capability by up to an order of magnitude, even at the low concentration of carbonate typically encountered in natural seawater. Our findings indicate a mechanistic framework of OER via multiple routes and provide a theoretical exploration for interfacial chemical-field regulation, inspiring promising strategies to overcome kinetic barriers in complex electrochemical systems for sustainable hydrogen generation.