A large-scale synthesis of photoluminescent carbon quantum dots: a self-exothermic reaction driving the formation of the nanocrystalline core at room temperature

Carbon quantum dots (CQDs), a rising star family in photoluminescent (PL) nanomaterials, have been identified to have a core-shell structure with the nanocrystalline core of sp(2)-hybridized carbon clusters and the functional group formed shell of sp(3)-hybridized carbons, in which the core formation usually needs high-temperature carbonization. Herein, we develop a route to prepare CQDs on a large scale by using hydroquinone and ethylenediamine (EDA) as the precursors and the EDA-catalyzed decomposition of hydrogen peroxide at room temperature. The released heat from this highly exothermic reaction system can rapidly prompt the formation of the nanocrystalline core. The as-prepared CQDs in situ show green PL properties around 525 nm under excitation at 320 to 420 nm with the absolute quantum yield of 24.6%, and can find applications in visual analysis and other fields.