Direct Natural Seawater Electrolysis through a Photoinduced Asymmetric Electric Field

Abstract

Direct natural seawater electrolysis offers a pathway for green hydrogen production, yet its industrialization is hindered by precipitation formation and sluggish water dissociation kinetics on the cathode. Herein, we propose a photoinduced asymmetric electric field (PAEF) that dynamically affects the interfacial H-bond network under illumination, forming OH – diffusion channels and reorienting water configurations. The transient absorption spectroscopy indicates carrier dynamics for PAEF in a designed photoresponsive catalytic system. The regulated interfacial water structure by PAEF avoids the formation of precipitate and lowers the water dissociation kinetic barrier on the cathode. Such a PAEF-enabled catalytic system shows a low overpotential of 299 mV at 100 mA cm –2 in natural seawater, with <5% activity decay after 100 h continuous operation. A light-assisted asymmetric electrolyzer (natural seawater in the cathode chamber) delivers 0.5 A cm –2 at 2.35 V (60 °C), while integration with the solar panel module maintains compatibility and a high solar-to-hydrogen efficiency (>10%) under fluctuating sunlight energy. By introducing an external light field, this work provides a scalable pathway for durable natural seawater electrolysis.