Solid-State Phosphors from Coal-Derived Carbon Quantum Dots

[Image: see text] With unique optical and chemical properties, carbon quantum dots (CQDs) find tremendous applications in chemistry, biology, and materials science to medicine. To expand the applicability of coal-derived CQDs from the liquid to solid state, we herein report the sustainable synthesis of solid phosphors from coal-derived CQDs using poly(vinyl alcohol) (PVA) and silica (SiO(2)) as an organic and inorganic matrix. Two coal-derived CQDs were obtained using an eco-friendly ultrasonic-assisted wet oxidation method. The structural and chemical properties of the CQDs were extensively investigated and compared with commercial CQDs. The coal-derived CQDs exhibited blue fluorescence with 8.9 and 14.9% quantum yields. The CQDs were found to be self-co-doped with nitrogen and sulfur heteroatoms through surface and edge functional groups. Solid-state fluorescence of PVA/CQD composite films confirmed that the CQDs retained their excellent blue emission in a dry solid matrix. A facile one-pot sol–gel method was employed to fabricate SiO(2)/CQD phosphors with the unique fluorescence emission. Due to their special structural features, coal-derived CQDs favored the heterogeneous nucleation and rapid formation of SiO(2)/CQD phosphors. Further, coal-derived CQDs caused high-intensity white light emission with CIE coordinates of (0.312, 0.339) by endowing a suitable band gap structure in a SiO(2)/CQD solid phosphor for potential optical applications.