Title : Microwave-assisted synthesis and structural investigation of coal-derived few ayer graphene via a catalytic graphitization process
Few-layer graphene was synthesized via microwave-assisted catalytic graphitization due to its increasing demand and wide applications. The microwave irradiation temperature at a set holding time played a key role in synthesizing few-layer graphene. The highest degree of graphitization and a well-developed pore structure was fabricated at 1300 °C using a 10% iron catalyst for 20 min. A high-resolution transmission electron microscopy analysis confirmed that the fabricated few-layer graphene consisting of 2–7 layers. In addition, the 2D band at 2700 cm−1 in the Raman spectrum indicated the presence of graphene layers. The Raman mapping also represented the catalyst loaded sample was homogeneously distributed and displayed a few-layer graphene sheet. The highest I2D/IG value indicated a few-layer graphene sheet. The few-layer graphene growth process was induced when iron oxide was reduced to metallic iron. The graphene nucleation and growth occurred via the dissolution-precipitation mechanism of bituminous coal and catalyst droplets. Finally, the synthesis of graphene using the traditional heating method takes around two weeks and over the higher temperature at 3000 °C. While the microwave graphitization required only 20 min and was much faster than the traditional heating method, moreover, the few-layer graphene precursor, i.e. coal, was abundant and inexpensive material. This technique assists in developing a cost-effective and environmentally friendly few-layer fabrication method using a coal-based carbonaceous material.