Morphological insights into uncompetitive fluorescence of coal-based carbon dots and strategies for improvement

The findings of the research indicate that coal-derived carbon dots (CDs), produced through top-down methods, exist as a blend of graphene quantum dots (GQDs), carbon quantum dots (CQDs), and carbon nanodots (CNDs). Within this mixture, numerous individual particles are dispersed, each containing multiple sp 2 -carbon domains, suggesting the presence of multiple fluorescent centers of varying sizes. These fluorescent centers scatter photon energy, leading to a wide full width at half maximum (FWHM >80 nm). To tackle this issue, the study significantly improves the fluorescence efficiency of coal-based CDs by employing a nitrogen-doping approach. Additionally, these nitrogen-doped CDs are combined with polyvinyl alcohol (PVA) to formulate secure inks exhibiting solid-state fluorescence and room-temperature phosphorescence (RTP) properties, showcasing their potential for anti-counterfeiting applications in safeguarding important documents and artworks.