Review on Phenylenediamine derived carbon dots and their applications

Carbon dots (CDs), as a novel type of fluorescent nanomaterial derived from graphene, carbon nanotubes, small organic molecules, polymers, biomass, and so on, have been highly popular in the optical field since it was discovered in 2004. Phenylenediamine C 6 H 4 (NH 2 ) 2 (PD), containing highly reactive amino groups, can be oxidized or polymerized under specific conditions to produce various products, which can be further polymerized, cross-linked and carbonized to obtain CDs. In recent years, CDs synthesized from PD as a precursor or as the main precursor have distinguished themselves in many research fields due to unique physical and chemical properties, including very impressive biocompatibility, negligible toxicity and exceptional performance of adjustable photoluminescence (PL) emission. Herein, we review the latest developments of CDs synthesized from PD as the single precursor or the main precursor, including a series of different preparation methods, different PL properties and possible luminous mechanisms. Furthermore, the review outlines the diverse applications of CDs in fields such as biomedical engineering, optical anti-counterfeiting, sensing and light-emitting diodes (LEDs), while also addressing the challenges and future prospects associated with CDs synthesized from PD as the single precursor or the main precursor.