Graphene-Like MoS_2/Graphene Composites: Cationic Surfactant-Assisted Hydrothermal Synthesis and Electrochemical Reversible Storage of Lithium

摘要

A cationic surfactant-assisted hydrothermal route is developed for the facile synthesis of graphene-like MoS_2/graphene (GL-MoS_2/G) composites based on the hydrothermal reduction of Na2MoO_4 and graphene oxide sheets with L-cysteine in the presence of cetyltrimethylammonium bromide (CTAB), following by annealling in N_2 atmosphere. The GL-MoS_2/G composites are characterized by X-ray diffraction, electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The effects of CTAB concentration on the micro structures and electrochemical performances of the composites for reversible Li~+ storage are investigated. It is found that the layer number of MoS_2 sheets decreases with increasing CTAB concentration. The GL-MoS_2 sheets in the composites are few-layer in the case of 0.01-0.03 mol L~(-1) CTAB of hydrothermal solution and single-layer in the case of 0.05 mol L~(-1) CTAB. The GL-MoS_2/G composites prepared with 0.01-0.02 mol·L~(-1) of CTAB solution exhibit a higher reversible capacity of 940-1020 mAh g~(-1), a greater cycle stability, and a higher rate capability than other samples. The exceptional electrochemical performance of GL-MoS_2/G composites for reversible Li~+ storage could be attributed to an effective integration of GL-MoS_2 sheets and graphene that maximizes the synergistic interaction between them.