Facile hydrothermal synthesis of MoS2 nano-sheets with controllable structures and enhanced catalytic performance for anthracene hydrogenation

MoS2 nano-sheets with controllable structures were prepared using a hydrothermal method. Effects of crystallization time, temperature and pH of the precursor solution on the structures, components and morphologies of MoS2 nano-sheets were investigated. MoS2 nano-sheets were characterized using XRD, Raman, elemental analysis, TG/DTG, SEM, and HRTEM. The characterization results show that intercalated MoS2, intermediate MoS2 with intercalated and semi-crystallized structures, and well crystallized hexagonal MoS2 (denoted as 2H-MoS2) were prepared by varying crystallization conditions, especially crystallization time. Intercalated MoS2 possesses rich active sites and poor crystallinity. 2H-MoS2 demonstrates high crystallinity but few active sites. As a transition structure during the crystallization process from intercalated MoS2 to 2H-MoS2, intermediate MoS2 simultaneously possesses rich active sites and good crystallinity. The possible growth mechanism of MoS2 nano-sheets in the hydrothermal process was proposed. The catalytic activities of MoS2 nano-sheets with various structures were evaluated by anthracene hydrogenation. The evaluation results show that intermediate MoS2 exhibits optimized catalytic activities of anthracene hydrogenation, which can be ascribed to the abundant active sites and desired stability of intermediate MoS2. This work may provide theoretic guidance for creating active sites and tuning catalyst structure for the controllable synthesis of layered transition metal sulfides with high catalytic activities.