Elsevier

Materials Letters

Volume 68, 1 February 2012, Pages 416-418
Materials Letters

Graphene sheets/Ag2S nanocomposites: Synthesis and their application in supercapacitor materials

https://doi.org/10.1016/j.matlet.2011.11.006Get rights and content

Abstract

Graphene-based nanocomposites are emerging as a new class of materials that hold promise for many applications due to their unique nanostructure and particular properties. In this paper, a novel graphene sheets/Ag2S composite was synthesized through a facile solvothermal method and its electrochemical performance was carried on a modified glassy carbon electrode (GCE) in a three-electrode electrochemical cell. The microstructure and morphology of the composites were characterized by X-ray diffraction and field emission scanning electron microscope. The results revealed that β-Ag2S nanoparticles (NPs) with an average size of ca. 53 nm were uniformly deposited on the surface of graphene sheets (Gs). The composite materials showed better electrochemical performance than the pure individual components and can be employed as supercapacitor materials.

Graphical abstract

Highlights

► We first synthesized graphene sheets/Ag2S nanocomposites via a solvothermal method. ► The method helps to understand the preparation mechanism of graphene-based materials. ► The Gs-Ag2S composites would be a promising candidate as supercapacitor materials.

Introduction

Graphene, a one-atom thick sheet of sp2-bonded carbon atoms, has attracted tremendous attention in both the experimental and theoretical scientific communications in recent years [1], [2]. Because of its unique nanostructure and extraordinary properties, graphene sheets are attractive as ideal nanoscale building blocks for new materials [3]. To explore the potential application of graphene-based materials, a great interest is nowadays devoted to graphene sheets doped with nanosized crystals of metals or semiconductors, often metal oxide or sulfide, for the development of electronic and optical devices with unique electrical and optical properties. So far, numerous graphene-based nanocomposites have been successfully synthesized and show desirable combinations of these properties that are not found in the individual component [4], [5].

Herein, we reported a novel graphene sheets/Ag2S nanocomposite which was in a solvothermal synthesis and showed enhanced electrochemical performance as supercapacitor material in a modified glassy carbon electrode.

Section snippets

Experimental

Graphite oxide was first prepared according to the modified Hummers method [6]. In a typical synthesis, the graphite oxide (200 mg) was dispersed in distilled water (200 mL) by vigorous ultrasonication for 1 h to get an exfoliated graphene oxide (GO) suspension, and ammonia (28 wt.%) was used to adjust the pH to around 12. Then, AgNO3 (100 mg) and CS(NH2)2 (100 mg) were put into the above suspension. The ammonia promised it to obtain maximal charge so as to prevent the aggregation of graphene oxide

Results and discussion

Fig. 1a is the illustration of deposition of Ag2S on the Gs. It is well-known that some carbon double bonds were oxidized after the acidic intercalation and thermal treatment, resulting in the presence of oxygen-containing functional groups such as single bondCOOH, and single bondOH on the surface of the graphene nanosheets [8]. Meanwhile, the amount and distribution of the carboxylic groups have great influence on the further positive-selective modification of graphene sheets with nanoparticles. The positive metal

Conclusions

In summary, a graphene-based Ag2S nano-structure composite has been successfully synthesized from GO by the solvothermal method. GO has been simultaneously reduced to graphene nanosheets during the deposition of Ag2S NPs. The XRD pattern revealed that the silver sulfide NP in nanocomposites is β-Ag2S, which has an average size of 53 nm. The SEM analysis confirmed the uniform attachment of Ag2S NPs on the graphene nanosheets. Electrochemical performance showed that the Gs–Ag2S composites

Acknowledgments

The authors would like to thank the financial support from the Natural Science Foundation of Gansu Province (0803RJZA009; 1010RJZA023), and supported by the fund of the State Key Laboratory of Solidification Processing in NWPU (SKLSP201011).

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