Simple route for gram synthesis of less defective few layered graphene and its electrochemical performance

Abstract

The mass production of high-quality graphene (GN) sheets is essential for their practical applications on a large scale. This paper reports a simple and less corrosive technique for the electrochemical exfoliation of graphite sheets using an aqueous solution mixture of sodium hydroxide, sodium thiosulfate, and sodium hypochlorite (NaOH + Na₂S₂O₃ + NaClO₄) as an electrolyte. The presence of NaClO₄ expanded the graphite lattice. NaOH in the electrolyte facilitated the electrochemical reduction of the preformed oxygen functional groups on GN while the sulphate ions of Na₂S₂O₃ accelerated the exfoliation of the graphite sheet. Along a series of chemical reactions, the oxidation process produced O₂ and SO₂ gases. These gases exerted additional forces on the graphite layers and separated the loosely bonded graphite layers, thereby accelerating the exfoliation process. The methodology produces large quantities of crystalline and high quality GN with few layered structures, and was thus called as few layered graphene (FLGN). The prepared FLGN was characterized using a range of techniques, including Raman spectroscopy and atomic force microscopy, which showed that the as-prepared FLGN has 4–6 layers and a large lateral size, which was also confirmed by other analysis. The electrochemical properties of FLGN were examined by cyclic voltammetry, impedance spectroscopy and charge/discharge studies. The as-prepared FLGN exhibited a high specific capacity and good cyclic stability, which makes this methodology promising for the large scale production of FLGN for practical applications.