State-of-the-Art on the Preparation, Modification, and Application of Biomass-Derived Carbon Quantum Dots

Carbon quantum dots (CQDs), as a novel fluorescent carbon nanomaterial, have raised worldwide concern on account of their remarkable biocompatibility, water solubility, chemical stability, nontoxicity, high conductivity, and turntable photoluminescence properties. Research on CQDs has been implemented for a dozen years, involving numerous precursors, synthesis methods, properties, and applications. Among them, the conversion of biomass waste into value-added CQDs has been considered as a green synthesis route for CQDs fabrication owing to its low cost, sustainability, environmental friendliness, and commercialization. This review focuses on the promising biomass-derived CQDs, including their advanced synthesis strategy, formation mechanism, modification technology, and application. The innovative up–down joint technique shows great potential in large-scale production of biomass-derived CQDs. The modification technology (size and shape control, heteroatom doping, surface passivation, composites) enables the tuning of their properties for high-quality products. It hopes to provide a comprehensive understanding of biomass-derived CQDs and guidance for future CQDs research directions.