Ultraviolet and blue emitting graphene quantum dots synthesized from carbon nano-onions and their comparison for metal ion sensing

Ultraviolet and blue emitting graphene quantum dots (GQDs) were synthesized by chemical oxidation of carbon nano-onions. TEM, AFM, XPS, and optical characterization techniques showed that different optical properties of UV-and blue-emitting GQDs originate from their unique structure and chemical functionalities. UV-and blue-emitting GQDs were also compared for heavy metal ion sensing.