Regulating Cocatalyst Spin‐Electronic Structures for Achieving Solar‐To‐H₂ of 7.32% in Photothermal‐Catalytic H₂O Overall Splitting

Precise regulation of intrinsic electronic structure of cocatalyst functional material for triggering photocatalyst activity at ultrafast‐spatiotemporal atomic levels is crucial to liberate photocatalytic efficiency. Herein, gradient spin‐state Ni 2 P as cocatalyst simultaneously including spin‐electronic configurations of tetra‐ (Ni 2+ ─(P) 4 ) and penta‐coordination (Ni δ+ –(P) 5 ) is designed for amplifying In 2 S 3 polarization by spin‐orbit coupling. So photo‐generated e − and h + from the In 2 S 3 photocatalyst vectorially transfer to Ni 2 p and In 3 d as redox active sites with charge density enhanced to ≈9.48 and 8.52 folds and long lifetime up to 289% (180.39 ns). Observably, energetic chemical adsorption and activation for *H and *OH at Ni 2 p and In 3 d are completed through electron nimble transfer into the corresponding orbits, performing an activation energy for H 2 O splitting down to ≈59%. Also, the gradient spin‐polarized photocatalytic system with the two regulated electronic structures of Ni 2 P as cocatalyst presents a remarkable productivity for solar energy conversion into H 2 of 7.32% at 75 °C under AM 1.5 G irradiation through *OH dehydrogenation and *H coupling paths, ranking in one of the best H 2 ‐generation catalysts for photocatalytic H 2 O overall splitting. This research first paves a novel path to completely unlock photocatalytic efficiency through regulating spin‐electronic structures of cocatalysts.