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 Ni2P as cocatalyst simultaneously including spin-electronic configurations of tetra- (Ni2+─(P)4) and penta-coordination (Niδ+-(P)5) is designed for amplifying In2S3 polarization by spin-orbit coupling. So photo-generated e- and h+ from the In2S3 photocatalyst vectorially transfer to Ni 2p and In 3d 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 2p and In 3d are completed through electron nimble transfer into the corresponding orbits, performing an activation energy for H2O splitting down to ≈59%. Also, the gradient spin-polarized photocatalytic system with the two regulated electronic structures of Ni2P as cocatalyst presents a remarkable productivity for solar energy conversion into H2 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 H2-generation catalysts for photocatalytic H2O overall splitting. This research first paves a novel path to completely unlock photocatalytic efficiency through regulating spin-electronic structures of cocatalysts.