Abstract text (incl. figure legends and references)

Graphene quantum dots (GQDots) have outstanding properties such as low toxicity, high biocompatibility, tunable fluorescent emission, high stability, and great versatility due to their abundant edges that allow their chemical functionalization. In this sense, it is necessary to have synthesis methods that allow their production in a controlled manner, being of low cost and low environmental impact. Therefore, in this study GQDots functionalized with amino groups were obtained by means of hydrothermal synthesis. The synthesis starts by obtaining graphene through the electrochemical exfoliation of graphite, its subsequent oxidation by the modified Hummers' method, and finally applying the hydrothermal treatment to this oxide. The materials obtained in this process were characterized by different microscopic and spectroscopic techniques. Atomic force microscopy confirmed that graphene nanosheets of 6.02 ± 2.73 nm wide and 1.04 ± 0.32 μm long were obtained. On the other hand, spectroscopic techniques (UV-Vis and FTIR) allowed for verifying the effectiveness of Hummers' method for the oxidation of graphene nanosheets. After applying the hydrothermal treatment to the graphene oxide, using different reaction times and temperatures, the formation of GQDots was verified by atomic force microscopy. The expected amino functionalization of the GQDots was verified by FTIR spectroscopy. The optical properties of these quantum dots were studied by UV-Vis and fluorescence spectroscopy, showing that absorption mechanisms in UV-Vis spectrum function as secondary mechanisms of fluorescent emission. Also, GQDots with higher reaction times have stronger fluorescent emission. Finally, the GQDots were used to modify the surface of a glassy carbon electrode, studying the change in the electrochemical sensitivity of this electrode using cyclic voltammetry. GQDots under certain synthesis parameters can increase the electrochemical signal detected. However, the phenomenon that shields the interaction of the modified electrode surface is still unknown.