Modulating Electronic Structure of MoS₂ Nanosheets by Sulfide Enrichment‐Induced Vacancies for Enhanced Photocatalytic Hydrogen Production

Abstract Enhancing photocatalytic activity by changing the electronic structure of the catalyst is an effective strategy. 2H‐MoS 2 has semiconductor properties, and its unsaturated side S atom is the main active site for its photocatalytic activity. However, due to the weak S─H bond energy, its hydrogen adsorption capacity is weak. In this work, the electronic structure of MoS 2 is adjusted by S‐rich treatment, resulting in the formation of Mo vacancy (MoS 2 ‐V Mo ). The level of Mo vacancies was assessed using UV–vis diffuse reflectance spectroscopy (UV–vis DRS). As these vacancies can capture certain photogenerated electrons, thereby reducing the recombination of electron‐hole pairs. Through DFT calculation, it is found that the antibonding orbital electron filling of MoS 2 ‐V Mo is weakened, the bond energy of S─Mo bond is weakened, and the bond energy between S─H bond is enhanced, which is more conducive to proton adsorption. The photocatalytic activity for hydrogen evolution of MoS 2 ‐3, which underwent the optimal S‐rich treatment, achieved a remarkable rate of 2404.6 µmol g −1 h −1 in dye eosin Y (EY) sensitization system, significantly surpassing that of MoS 2 lacking the S‐enriched treatment. This study introduces a novel concept for enhancing the photocatalytic hydrogen evolution performance of metal sulfides via defect engineering.