From biomass to wealth: biomass-derived carbon dots for green synthesis, photoluminescence mechanisms, and multifunctional applications

Biomass-derived carbon dots (BCDs) have garnered significant interest as multifunctional nanomaterials owing to their inherent structural flexibility, exceptional biocompatibility, and environmental sustainability, positioning them as promising alternatives to conventional carbon dots derived from organic precursors. Current research mostly focuses on reporting “which biomass” can produce “which BCDs”, ignoring the critical link between precursor selection and the properties and applications of BCDs. This review provides a systematic analysis of research progress in BCDs, with a particular emphasis on precursor selection, synthesis methods, photoluminescence mechanisms, and diverse applications. The review also highlights the utilization of abundant biomass resources, including plant and animal derivatives, microorganisms, and plastic waste, for the green synthesis of BCDs. Different synthesis strategies are critically evaluated for their efficiency, scalability, and environmental impact. The photoluminescence mechanisms of BCDs are discussed to reveal their complex structure-property relationships, and feasible methods to distinguish these mechanisms are proposed. Furthermore, the applications of BCDs in bioimaging, sensing, optoelectronics, anti-counterfeiting, and other fields are comprehensively reviewed. Bio/environmental safety, industrialization challenges, and future perspectives are outlined to guide the rational design of BCDs for next-generation technologies. This review endeavors to close the divide between fundamental research and practical applications, emphasizing the role of BCDs in advanced green sustainable nanotechnology. • The fluorescence mechanism of biomass-derived carbon dots (BCDs) was summarized. • A clear “structure-property” linkage between biomass precursor and the resulting properties and applications of BCDs was established. • A novel energy input-based classification criterion for synthesis methods of BCDs was proposed.