Synthesis of Reduced Graphene Oxide Through Microwave Irradiation of Graphene Oxide Derived from Vein Graphite for the Anode Application in Li-Ion Rechargeable Batteries

Abstract

Among several methods being pursued to synthesize graphene, thermal reduction of Graphene Oxide (GO) has been identified as a straightforward and highly efficient method for scalable graphene production. However, high energy consumption is a significant limitation faced by this method. Microwaves, an alternative energy input source, have been widely used in many technological fields. Although graphene is an excellent microwave absorbent, GO has a poor microwave absorption capacity. Therefore, it needs a microwave absorbent like graphene to carry out the microwave reduction of Graphene Oxide. Therefore, the objective of this study is to synthesize reduced Graphene Oxide (rGO) using purified Sri Lankan vein graphite as the starting material through microwave irradiation without the use of a microwave absorbent such as graphene. First, Graphene Oxide was prepared using Tour's method, and Graphite Oxide Intermediate (GOI) was collected before washing and neutralizing the product. It was then treated separately in a domestic microwave oven at 900W power for 15 and 20 minutes. GOI turned black from brown after microwave irradiation took place for 20 min. The reduction of functional gr oups was confirmed by Fourier Transformed Infrared (FTIR) spectroscopy and X-ray diffraction study confirmed the formation of the reduced graphene oxide with the significant peak doo2 reappearing at 24.95 •, corresponding to an inter-planer spacing of0.365 nm, which is comparable to that of the thermally reduced graphene oxide. Scanning electron microscopic analysis showed evidences of the existence ofan expanded 'worm-like" morphology of the graphite layers. These characterizations proved that the microwave irradiation had reduced Graphene Oxide without the addition of a microwave absorbent. In an electrochemical performance investigation conducted by assembling Li-ion half-cells, the anode electrode fabricated from the synthesized microwave reduced graphene oxide material showed a promising capacity of 266. 7 mAh g-1 Vs. Li/Li + . This study revealed the ability to successfully synthesize reduced graphene oxide through microwave irradiation without using a microwave absorbent starting with natural vein graphite for the anode application in Li-ion rechargeable batteries.