Green synthesis of biomass carbon nanodots and their multifunctional applications.

Carbon quantum dots (CQDs) have garnered significant attention as an emerging fluorescent nanomaterial due to their simple preparation, abundant raw material sources, excellent biocompatibility, and unique optical properties. Among these advantages, the preparation of CQDs using renewable biomass resources-such as agricultural residues, food waste, or forestry byproducts-not only aligns with green chemistry principles but also paves a sustainable path for their low-cost, large-scale production and application. This paper systematically reviews mainstream methods for synthesizing CQDs from biomass, including hydrothermal treatment, high-temperature pyrolysis, and microwave-assisted synthesis, and provides a detailed analysis of how different preparation strategies influence the morphology, structure, and optical performance of the resulting CQDs. Furthermore, the review highlights recent advances in the application of biomass-derived CQDs across multiple frontier fields: as fluorescent sensors for detecting metal ions and vitamins; as efficient probes in bioimaging; as functional layers in optoelectronic devices to enhance performance; and as security inks for information encryption and anti-counterfeiting. Finally, the paper addresses current challenges in this field-such as the limited range of emission colors and insufficient understanding of the formation and luminescence mechanisms-and outlines future research directions, emphasizing the potential of biomass-derived CQDs to facilitate the development of sustainable advanced materials.