Single-atom cerium-induced spin-pinning effect on NiFe-LDH for ultra-efficient solar-driven seawater splitting.

Direct seawater electrolysis is a promising pathway for green hydrogen production but is severely hindered by the sluggish oxygen evolution reaction (OER) kinetics and chloride-induced corrosion at the anode. Herein, we report a single-atom catalyst consisting of atomically dispersed Ce anchored on NiFe-layered double hydroxide (Ce1/NiFe-LDH) that addresses both challenges simultaneously. Isolated Ce3+ species with a 4f1 electronic configuration modulate the spin state of adjacent Fe sites through Ce-O-Fe bridging motifs. This interfacial d-f orbital hybridization induces a spin-pinning effect that drives Fe toward a high-spin configuration, optimizing the adsorption energetics of oxygen intermediates via quantum spin exchange interaction and drastically lowering the OER overpotential. Ce1/NiFe-LDH requires only 80 mV and 120 mV overpotentials to achieve 100 mA cm-2 in simulated and natural seawater, respectively, with an exceptionally low Tafel slope of 20.82 mV dec-1. When integrated into a photovoltaic-electrolysis device, it delivers a solar-to‑hydrogen efficiency of 14.47% under natural sunlight. This work establishes single-atom spin-state tuning as a powerful strategy for designing robust electrocatalysts for sustainable energy conversion.