Ponente
Descripción
Graphene oxide (GO) and carbon quantum dots (CQDs) are emerging carbon-based nanomaterials with unique physical, chemical, and optical properties, making them attractive for a wide range of applications in fields such as electronics, energy, biomedicine, and environmental science. The synthesis of these nanostructures in the Submerged Arc Discharge in Water (SADW) was first described recently by our research group. Herein, we report on the photoluminescence (PL) and optical properties of the GOs and CQDs synthesized by SADW. The structural and optical properties of the synthesized GO and CQD were characterized using high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), Fourier-transform infrared (FTIR) spectroscopy, UV-Vis absorption spectroscopy, and fluorescence spectroscopy. The HRTEM analysis showed that CQDs synthesized by SADW have diameters ranging from 1 to 5 nm. AFM analysis of that GOs had a typical maximum extension of 5-20 µm, an average area of 20-300 µm2 and an estimated number of layers of 6-10. The PL of CQDs and GOs synthesized by DASA was found to be independent of excitation wavelength due to their more ordered surface structure compared to those produced by Bottom-Up methods. This is linked to a complex balance between the edge fluorophore-like systems and the real electronic transitions in the confined π-conjugated system of its nucleus, which indicates the relatively large degree of internal order of the SADW CQDs and GOs. CQDs presented three PL bands in the range of 320 - 470 nm and a quantum yield (QY) of 17% against Rhodamine 6G one of the largest ever reported for top-down CQDs. SADW GOs were found to present a moderate multiphotonic PL band in the 690 – 800 nm region.
