Excitons in graphene have an infi nite Bohr diameter. Thus, graphene fragments of any size will show quantum confi nementeffects.[20] As a result, GQDs have a non-zero bandgap andluminesce on excitation. This bandgap is tunable by modifyingthe size and surface chemistry of the GQDs.[21] Density functional theory (DFT) calculations have shown that the bandgapof GQDs increases to approximately 2 eV in a GQD consistingof 20 aromatic rings and 7 eV for benzene.[22] Very little workhas been done on the electronic properties of GQDs and apartfrom some early electrochemical measurements in the contextof electrosynthesis, electrocatalysis, and sensing, there is verylittle known.
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