Simple and Environment-Friendly Method for Graphene Synthesis by Using Ultrasound

Abstract

Background: This paper proposes a technology for the production of monolayer graphene by an easy, acscessible, and non-toxic method. Methods: For the preparation of graphene, a combination of chemical and physical (ultrasonic) treatment of the original graphite precursor (purity >99%) was applied. The precursor of graphite is placed in a beaker with a solution of KOH or H2SO4. The mixtures were homogenized well and sonicated for 4h. The applied ultrasound has a power of 120 W, frequency 40 kHz. Due to the effects of ultrasound, complex processes take place in the solutions, which leads to the formation of superfine graphene. Better results were obtained at samples treated with 2n H2SO4. The physicochemical properties of the resulting graphene were characterized mainly by Raman spectroscopy, FT-IR, TEM, SEM, and electrical conductivity measurements. Results: Our research was focused mainly on the field of nanotechnology, in particular on the synthesis of graphene, which could be used as a coating on electrodes for supercapacitors. In this connection, three series of samples were developed in which the pristine graphite was treated with 2n H2SO4, 4n H2SO4, and 6n H2SO4, respectively, and their electrical properties were measured. Conclusion: The obtained graphene shows electrical resistivity 2-3 times lower than that of the precursor of pure graphite.