A 17.73 % Solar‐To‐Hydrogen Efficiency with Durably Active Catalyst in Stable Photovoltaic‐Electrolysis Seawater System

Developing durably active catalysts to tackle harsh voltage polarization and seawater corrosion is pivotal for efficient solar-to-hydrogen (STH) conversion, yet remains a challenge. We report a durably active catalyst of NiCr-layered double hydroxide (Ru_ldsNiCr-LDH) with highly exposed Ni-O-Ru units, in which low-loading Ru (0.32 wt %) is locked precisely at defect lattice site (Ru_lds) by Ni and Cr. The Cr site electron equilibrium reservoir and Cl^- repulsion by intercalated CO₃ ^2- ensure the highly durable activity of Ni-O-Ru units. The Ru_ldsNiCr-LDH‖Ru_ldsNiCr-LDH electrolyzer based on anion exchange membrane water electrolysis (AEM-WE) shows ultrastable seawater electrolysis at 1000 mA cm^-2. Employing Ru_ldsNiCr-LDH both as anode and cathode, a photovoltaic-electrolysis seawater system achieves a 17.73 % STH efficiency, corresponding photovoltaic-to-hydrogen (PVTH) efficiency is 72.37 %. Further, we elucidate the dynamic evolutionary mechanism involving the interfacial water dissociation-oxidation, establishing the correlation between the dynamic behavior of interfacial water with the kinetics, activity of Ru_ldsNiCr-LDH catalytic water electrolysis. Our work is a breakthrough step for achieving economically scalable production of green hydrogen.