Optimizing Atomic Hydrogen Desorption of Sulfur‐Rich NiS<sub>1+</sub><i><sub>x</sub></i> Cocatalyst for Boosting Photocatalytic H<sub>2</sub> Evolution
Duoduo Gao, Jiachao Xu, Linxi Wang, Bicheng Zhu, Huogen Yu, Jiaguo Yu
Abstract
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 (SH 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 SH 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.