Controlling the emissive pathways of carbon nanoparticles by selective surface functionalization

Environmental friendly and biocompatible fluorescent carbon nanoparticles (CNPs) show great potential for various applications. The functional groups on the surface of the NPs dramatically influence the absorption and emission characteristics of the particles. However, a conclusive emission mechanism of CNPs and the exact role of functional groups are still lacking. Herein, a systematic investigation has been carried out by quantifying the oxygen-based function groups (-OH, -CHO, -COOH, -CO, -COO) present on the surface of activated carbon (AC) nanoparticles to identify their role in the emission characteristics. AC samples, prepared by the activation process of green waste of mandarin peels, were subjected to further treatments to achieve different levels of surface functionality with oxygen containing functional groups such as carbonyl, carboxyl, phenol and lactone. Various characterization techniques were employed to identify and quantify the functional groups. A detailed emission study revealed the role of specific functional groups in the emission process. Our results suggests that various emissive pathways in CNPs can be controlled by selective surface functionalization. This study shows significant results, which could shed more light on the emission mechanism of CNPs and the pivotal role of surface functional groups.