Organic amine-grafted carbon quantum dots with tailored surface and enhanced photoluminescence properties

A facile one-step synthesis strategy has been developed for producing fluorescent carbon quantum dots (CQDs) from a kind of Chinese coal, Jincheng anthracite. Surface grafting of the CQDs was completed and systematically investigated by grafting with a series of organic amino molecules. It was found that the solubility and the optical properties of CQDs vary with and depend on its surface chemistry to some degree. Of organic amine-grafted coal-derived CQDs available now, ethylenediamine-grafted CQDs (EDA-CQDs) possess an obviously enhanced photoluminescence (PL) with the quantum yield (QY) as high as 18.6%, being an increase of 24.5 times in comparison with that of the pristine CQDs (0.73%), and have a capability of well dispersing within other polymer matrixes due to their good compatibility after amine-grafting. The hybrid monolith made of amine-grafted CQDs and polymer gelatin exhibits excellent PL properties even at a relatively high concentration of CQDs, indicative of great potential applications in various optical materials and devices.