Solvothermal conversion of coal into nitrogen-doped carbon dots with singlet oxygen generation and high quantum yield

Fluorescent nitrogen-doped carbon dots (N-CDs) are synthesized by a facile one-pot solvothermal approach from Taixi anthracite in the presence of dimethyl formamide (DMF). Benefiting from superior dispersion of light components in DMF and easy exfoliation of smaller sp²-carbon structures from the anthracite, the as-prepared N-CDs show a strong photoluminescence (PL) with a high quantum yield (QY) of 47.0% and production yield of 25.6 wt%. Besides, the N-CDs also exhibit a singlet oxygen (¹O₂) generation behavior with a ¹O₂ generation QY of 19.0%. Moreover, the as-obtained N-CDs emit blue PL under the excitation wavelength of 365 nm, and can be easily dispersed in polymethyl methacrylate (PMMA), retaining the inherent advantages of the N-CDs and the PMMA matrix. The possible mechanism involved in the formation of N-CDs is proposed and discussed in terms of the macromolecular structure of the anthracite and the solvothermal approach adopted in the study.