Fast chemical exfoliation of graphite to few-layer graphene with high quality and large size via a two-step microwave-assisted process

Scalable preparation of graphene with both large size and high quality is an important prerequisite for fully realizing its commercial use. Herein, we propose a high-efficient route for preparing few-layer graphene, in which the chemical exfoliation of graphite to similar to 100% few-layer graphene can be realized within only about 15 min by using a novel two-step microwave irradiation strategy. The as-obtained graphene sheets behave a few-layer feature (average layer number <= 5 layers) and possess large size (the average area size is up to 256.8 mu m(2)). The graphene film prepared from the obtained graphene sheets exhibits an excellent electrical conductivity of up to 2.03x10(5) S m(-1), among the highest ones reported so far for the graphene, suggesting the high quality of the prepared graphene. Most importantly, no water-washing and effluent-treatment are needed during the whole preparation process, which will greatly reduces the consumption of water resource and alleviates the environmentally detrimental impact caused by the effluent of used chemicals compared with those conventional chemical exfoliation routes. Benefiting from its simplicity, high-efficiency and high-quality, the present method will show great promise for the mass production of high-quality graphene sheets.