Recent advances of biomass-derived carbon dots with room temperature phosphorescence characteristics

Carbon dots (CDs) as a new type of room temperature phosphorescence (RTP) materials possess great advantages, such as low cost, simple preparation, high biocompatibility, especially exhibiting more diverse structural designs and better luminescence tunability. However, most of current RTP CDs are derived from organic chemicals, which will inevitably increase the consumption of resources and endanger the ecological environment in the long run. Biomass, as natural, abundant, and renewable carbon resource has been used in preparing RTP CDs. The aromatization structure, abundant -OH, -COOH, -NH2 groups, etc., heteroatom self-doping performance of biomass are conducive to the construction of conjugated carbon cores and RTP active sites (C--O/C--N) of CDs. Moreover, the biomass-derive RTP CDs also solve the biowaste problem, reduce production costs, achieve sustainable carbon development and effectively promote the reuse of resources, simultaneously. Nevertheless, although the RTP characteristics of biomass-derived CDs have been discovered and made significant progress, there was not any review article being published to provide a systematic summary of these progress. Here, a summary of the recent progress on biomass-derived RTP CDs, such as the structure composition, luminescence mechanism, property regulation, synthetic approaches, and potential applications is given. Firstly, a brief introduction is given to the apparent composition and carbon core structure of biomass-derived RTP CDs. Then, the RTP luminescence mechanism are summarized based on two aspects, including matrix-free and matrixprotected biomass-derived RTP CDs. Moreover, the regulation of RTP properties from kinds of biomass raw materials, preparation methods, heteroatom doping and composite matrix is presented aiming to highlight the unique advantages of biomass to prepare RTP CDs. Afterwards, the potential applications of biomass-derived RTP CDs, such as anti-counterfeiting, information encryption, sensing, light emitting diodes and biological applications, etc., are reviewed. Finally, the current challenges and further prospects on the development of biomassderived RTP CDs are proposed.