Carbon quantum dots synthesis from waste and by-products: Perspectives and challenges

Abstract Carbon dots (CDs) are a novel class of fluorescent nanomaterials, with properties such as photoluminescence, high solubility, low toxicity, and favorable biocompatibility. They are useful for applications in biomedicine, sensors, solar cells, and photocatalysis, among others. CDs synthesis using vegetal, animal, or industrial waste as a source has become a focus of interest among researchers. These waste materials are inexpensive and available at large, and the repurposing of natural resources has the potential to reduce pollutants and their environmental impacts. Residues from plant sources, such as peels, leaves, and flowers, are preferred over other sources, and the conversion to CDs is performed mainly through the hydrothermal method. However, some matters regarding this technology require further studies and elucidation, such as the increase CD’s conversion yield from the raw material. Thus, we aimed to explore the use of waste and by-products in CDs synthesis, their potentials, and advantages, as well as present current challenges in the field of study.