Chemical Functionalisation and Photoluminescence of Graphene Quantum Dots

Chemical modification of graphene quantum dots (GQDs) can influence their physical and chemical properties; hence, the investigation of the effect of organic functional groups on GQDs is of importance for developing GQD–organic hybrid materials. Three peripherally functionalised GQDs having a third‐generation dendritic wedge (GQD‐2), long alkyl chains (GQD‐3) and a polyhedral oligomeric silsesquioxane group (GQD‐4) were prepared by the CuI‐catalysed Huisgen cycloaddition reaction of GQD‐1 with organic azides. Cyclic voltammetry indicated that reduction occurred on the surfaces of GQD‐1–4 and on the five‐membered imide rings at the periphery, and this suggested that the functional groups distort the periphery by steric interactions between neighbouring functional groups. The HOMO–LUMO bandgaps of GQD‐1–4 were estimated to be approximately 2 eV, and their low‐lying LUMO levels (