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 (RuldsNiCr-LDH) with highly exposed Ni-O-Ru units, in which low-loading Ru (0.32 wt%) is locked precisely at defect lattice site (Rulds) by Ni and Cr. The Cr site electron equilibrium reservoir and Cl- repulsion by intercalated CO32- ensure the highly durable activity of Ni-O-Ru units. The RuldsNiCr-LDH‖RuldsNiCr-LDH electrolyzer based on anion exchange membrane water electrolysis (AEM-WE) shows ultrastable seawater electrolysis at 1000 mA cm-2. Employing RuldsNiCr-LDH both as anode and cathode, a photovoltaic-electrolysis seawater system achieves a 17.73% STH efficiency, corresponding photoelectricity-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 RuldsNiCr-LDH catalytic water electrolysis. Our work is a breakthrough step for achieving economically scalable production of green hydrogen.