ORIGINAL PAPER One-step electrochemical synthesis of MoS 2 /graphene composite for supercapacitor application Gomaa A. M. Ali 1,2 & Mohammad R. Thalji 1 & Wee Chen Soh 1 & H. Algarni 3,4 & Kwok Feng Chong 1 Received: 14 June 2019 /Revised: 13 November 2019 /Accepted: 14 November 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract In this study, an MoS 2 /graphene composite is fabricated from bulk MoS 2 and graphite rod via a facile electrochemical exfoliation method. The as-prepared samples are characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier trans- form infrared spectroscopy and ultraviolet-visible spectroscopy techniques to confirm the formation of the MoS 2 /graphene composite. The electrochemical behavior of the MoS 2 /graphene composite is evaluated through cyclic voltammetry, galvanostatic charge/ discharge and electrochemical impedance spectroscopy. It exhibits high specific capacitance of 227 F g -1 as compared with the exfoliated graphene (85 F g -1 ) and exfoliated MoS 2 (70 F g -1 ) at a current density of 0.1 A g -1 . This can be attributed to the synergistic effect between graphene and MoS 2 . Moreover, it displays high electrochemical stability and low electrical resistance. Keywords Electrochemical exfoliation . Supercapacitors . Graphene . Exfoliated MoS 2 . 2D materials Introduction Two-dimensional (2D) materials, such as graphene, have gar- nered great interest from researchers for decades due to their outstanding mechanical, optical and physical properties [1–3]. Besides graphene, transition metal dichalcogenides, particu- larly molybdenum disulfide (MoS 2 ), show promising poten- tial in a wide range of applications including as catalysts and for energy storage and electronics [4, 5]. Bulk MoS 2 crystals can undergo exfoliation to form MoS 2 (a single, covalently bonded S–Mo–S tri-layer). This is the top-down synthesis approach for MoS 2 . To date, various exfoliation approaches including sonication, ion intercalation and electrochemical ex- foliation have been used to produce high-quality MoS 2 [6]. MoS 2 is a semiconducting compound that consists of a 2D plane of a hexagonal crystal structure which is analogous to graphene [7, 8]. Each MoS 2 layer consists of planes wherein the S–Mo–S atoms are combined by covalent bonds, and their neighboring layers are then attached to each other by weak van der Waals forces [9, 10]. From the other point of view, each Mo atom occupies a trigonal prism shape which is bound to six S atoms. The layered structure of MoS 2 provides a good platform for ion adsorption and diffusion, rendering it a great choice for supercapacitor applications [11]. On the other hand, another layered structure material, graphene, also possesses excellent physical properties for good energy storage applica- tions [12, 13]. However, the major concern for layered struc- ture material is the tendency for restacking of sheets to occur, which has a detrimental effect on the energy storage capacity. In this context, the proposal for utilizing two different layered structure materials is worth investigating, as the different Highlights • An MoS 2 /graphene composite is obtained via one-step electrochemical exfoliation. • The MoS 2 /graphene composite is employed as electrode material for supercapacitor application. • MoS 2 /graphene shows high specific capacitance of 227 F g -1 (threefold > MoS 2 and graphene). • MoS 2 /graphene shows high electrochemical stability and low electrical resistance. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-019-04449-5) contains supplementary material, which is available to authorized users. * Kwok Feng Chong ckfeng@ump.edu.my 1 Faculty of Industrial Sciences & Technology, Universiti Malaysia Pahang, 26300 Kuantan, Malaysia 2 Chemistry Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt 3 Research Centre for Advanced Materials Science (RCAMS), King Khalid University, P. O. Box 9004, Abha 61413, Saudi Arabia 4 Department of Physics, Faculty of Sciences, King Khalid University, P. O. Box 9004, Abha, Saudi Arabia Journal of Solid State Electrochemistry https://doi.org/10.1007/s10008-019-04449-5