Constrained Growth of MoS<sub>2</sub> Nanosheets within a Mesoporous Silica Shell and Its Effects on Defect Sites and Catalyst Stability for H<sub>2</sub>S Decomposition

Molybdenum disulfide (MoS<sub>2</sub>) is a two-dimensional transition-metal dichalcogenide that can form layered nanosheets with catalytically active sites present at edge or defect sites. The density of such active sites can be further tuned by modifying the length, layer number, strain, and surface defects of the sheets. Herein, a synthetic approach has been developed to encapsulate nanoscale MoS<sub>2</sub> nanosheets inside a mesoporous silica shell. Small molybdenum­(IV) oxide (MoO<sub>2</sub>) cores were synthesized and coated with a mesoporous silica phase, followed by a conversion to MoS<sub>2</sub>@SiO<sub>2</sub>. The space constraint on the inner cores resulted in short, few-layered, highly curved MoS<sub>2</sub> nanosheets with circular or flowerlike morphology. The MoS<sub>2</sub>@SiO<sub>2</sub> was evaluated as a catalyst for decomposition of hydrogen sulfide (H<sub>2</sub>S), which shows high catalytic turnover frequency and superior thermal stability in comparison to unconstrained MoS<sub>2</sub> catalysts.