S, N co-doped graphene quantum dots fabricated by rapid microwave-assisted pyrolysis and their optical properties

Recently, graphene quantum dots (GQDs) have attracted the interest of scientists as a potential material for applications in antibacterial agents. Besides, low-cost synthesis, environmentally friendly, safe in use, easy-toperform technique is one of the urgent requirements to apply this material. This research presents the synthesis of sulfur (S) and nitrogen (N) co-doped GQDs (S,N-GQDs) by microwave-assisted pyrolysis, which is a rapid, simple, and green method, as well as improved their dispersion in water for antibacterial purposes. The particle size of fabricated S,N-GQDs was 3 nm. XRD patterns reveal that S,N-GQDs have a crystalline structure with a carbogenic core. Both the S pi* -* C pi and N pi* -* C pi transitions contribute to the luminescence of the S,N-GQDs material, whose local luminescence peaks at 448 nm, this peak changed with various pH values. High quantum yield depends on both the power of microwave and pH values.