Charging d‐Orbital Electron of ReS2+x Cocatalyst Enables Splendid Alkaline Photocatalytic H2 Evolution

Abstract Rhenium disulfide (ReS 2 ) holds expansive perspective in photocatalytic water‐splitting field, but its H 2 ‐production rate is severely impeded by the strong hydroxyl (OH ad ) adsorption on catalytic Re atoms. Herein, an ingenious strategy about charging d ‐orbital electrons of ReS 2+x cocatalyst by integrating metallic Au is explicitly clarified to effectively accelerate OH ad desorption for promoting alkaline photocatalytic H 2 ‐evolution activity. To this end, core‐shell Au@ReS 2+x nanostructures as H 2 ‐production cocatalysts are skillfully fabricated onto TiO 2 by a directional assembly pathway. Experimental and theoretical data validate an free‐electron transfer from metallic Au core to S‐rich ReS 2+x shell, thus essentially charging electrons to the d‐orbital of Re atoms to construct active Re (4‐ δ )+ sites. The charged d‐orbital electron state of Re (4‐ δ )+ atoms raises antibonding occupancy of the Re (4‐ δ )+ OH ad bonds, thereby accelerating OH ad desorption and endowing core‐shell Au@ReS 2+x cocatalysts an efficient H 2 production from alkaline water splitting. Moreover, the core‐shell Au@ReS 2+x cocatalysts can effectively capture photogenerated electrons from TiO 2 as unveiled by operando Kelvin probe force microscopy. Consequently, the optimized TiO 2 /Au@ReS 2+x photocatalyst achieves an exceptional H 2 ‐production rate of 6013.45 µmol h −1 g −1 with releasing visual H 2 bubbles in alkaline media. This research furnishes original insights for charging orbital electrons to optimize the adsorption strength between intermediates and catalytic atoms.