Structural and luminescent properties of CQDs produced by microwave and conventional hydrothermal methods using pelagic Sargassum as carbon source

The synthesis of carbon quantum dots (CQDs) from biomass could be the best application for biopolymeric materials with no further use in industry and that can have environmental effects when disposed of, such as pelagic Sargassum. This research compared the structural and luminescent properties of CQDs synthetized by two different methods (microwave and conventional hydrothermal synthesis) using pelagic Sargassum extract as a carbon source. The microwave method resulted in a better mass yield, while hydrothermal synthesis generated the best quantum yield (QY). Under optimized synthesis conditions, no statistical differences were observed in CQDs size or surface functional groups, as detected by TEM and FTIR analyses respectively. However, crystalline structure and light absorption varied between samples, explaining the higher values of QY observed in the conventional hydrothermal method. This study thus assists in furthering the understanding of the synthesis process, as well as providing supporting evidence for which synthesis methods are better for CDQ synthesis depending on the future uses of these nanoparticles.