Optimizing Atomic Hydrogen Desorption of Sulfur‐Rich NiS1+x Cocatalyst for Boosting Photocatalytic H2 Evolution

Abstract Low‐cost transition‐metal chalcogenides (MS x ) are demonstrated to be potential candidate cocatalyst for photocatalytic H 2 generation. However, their H 2 ‐generation performance is limited by insufficient quantities of exposed sulfur (S) sites and their strong bonding with adsorbed hydrogen atoms (SH ads ). To address these issues, an efficient coupling strategy of active‐site‐enriched regulation and electronic structure modification of active S sites is developed by rational design of core–shell Au@NiS 1+ x nanostructured cocatalyst. In this case, the Au@NiS 1+ x cocatalyst can be skillfully fabricated to synthesize the Au@NiS 1+ x modified TiO 2 (denoted as TiO 2 /Au@NiS 1+ x ) by a two‐step route. Photocatalytic experiments exhibit that the resulting TiO 2 /Au@NiS 1+ x (1.7:1.3) displays a boosted H 2 ‐generation rate of 9616 µmol h −1 g −1 with an apparent quantum efficiency of 46.0% at 365 nm, which is 2.9 and 1.7 times the rate over TiO 2 /NiS 1+ x and TiO 2 /Au, respectively. In situ/ex situ XPS characterization and density functional theory calculations reveal that the free‐electrons of Au can transfer to sulfur‐enriched NiS 1+ x to induce the generation of electron‐enriched S δ − active centers, which boosts the desorption of H ads for rapid hydrogen formation via weakening the strong SH ads bonds. Hence, an electron‐enriched S δ − ‐mediated mechanism is proposed. This work delivers a universal strategy for simultaneously increasing the active site number and optimizing the binding strength between the active sites and hydrogen adsorbates.