Interlayer transition in graphene carbon quantum dots

Abstract

Graphene Carbon Quantum Dots (GCQDs) are multi-layered carbon nanostructures that have attracted considerable attention due to its unique properties. Many technological applications, such as batteries, biological imaging, capacitors, solar cells, light emitting diodes, among others, could benefit from the low toxicity and the chemical and physical stability of these nanostructures. Despite much research, many optical properties, such as absorption and photoluminescence, of GCQDs are not completely understood yet. GCQD absorption spectra show a number of different bands whose origin is still on discussion. Many interpretations are made considering a single graphene layer. In this work, GCQD samples synthesized by the pyrolysis of citric acid was characterized by absorption spectroscopy measurements and Density Functional Theory simulations considering multi-layered structures. Density of States and electronic response functions calculations were also performed. From the results of these calculations, the absorption band associated to a π-π* (CC) transition could be also associated to a transition between different graphene layers.

Synthesis of Graphene Quantum Dots Coupled to Au Nanoparticles: A Facile and Versatile Route Using Different Carbon Sources

“…Graphene quantum dots (GQD) are an example of these graphene-based nanomaterials; the space of their structure is confined to nanometer scales (around 10 nm) in its three dimensions, thus having a single atomic layer thickness [1,4]. Though it is a relatively recent material, its quantum effects are theoretically well known in relation to its electronic properties (which are mainly edge effects that introduce low energy states), and various methods have been developed for their synthesis; it is essential to facilitate their obtaining in order to find useful applications for this novel nanomaterial [5,6].…”