Graphene-like MoS2/graphene composites: Cationic surfactant-assisted hydrothermal synthesis and electrochemical reversible storage of lithium

Abstract

A cationic surfactant-assisted hydrothermal route is developed for the facile synthesis of graphene-like MoS2/graphene (GL-MoS 2/G) composites based on the hydrothermal reduction of Na 2MoO4 and graphene oxide sheets with L-cysteine in the presence of cetyltrimethylammonium bromide (CTAB), following by annealling in N2 atmosphere. The GL-MoS2/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 microstructures and electrochemical performances of the composites for reversible Li+ storage are investigated. It is found that the layer number of MoS2 sheets decreases with increasing CTAB concentration. The GL-MoS2 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-MoS2/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-MoS2/G composites for reversible Li+ storage could be attributed to an effective integration of GL-MoS2 sheets and graphene that maximizes the synergistic interaction between them. Graphene-like (GL-) MoS2/graphene composites are prepared by a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process and following heat treatment. In the case of 0.01-0.02 mol L-1 CTAB, the GL-MoS2 in the composites displays a few-layer structure with an interlayer spacing of 0.63-0.64 nm and the composites exhibit a high capacity of 940-1020 mAh g-1 with excellent cycle stability and high-rate capability for electrochemically reversible Li+ storage. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.