Energy transfer between chemiluminescence (CL) donor and acceptor enables the tunable long-wavelength emission for multidisciplinary applications. In this work, the carbon nanodots (CDs) with sp³-hybrid carbon nitride framework exhibit a conspicuous tunable CL wavelength in luminol–H₂O₂ reaction with ultrahigh energy transfer efficiency. The density functional theorical calculations and experimental surveys reveal that the synergistic effect of singlet/triplet mixed electron exchange between the CD and luminol–H₂O₂ reaction enable the efficient energy transfer, and the concentration-dependent distance between the luminol donor and CD acceptor mutate the efficiency of singlet/triplet electron exchange, leading to the efficient concentration-dependent CL emission. With the novel CL emission, an advanced paper-based CL system is established with the CDs and luminol–H₂O₂ reaction, and the applications of information encryption and anti-counterfeiting are achieved. This work paves a new paradigm to understand the energy transfer mechanism in CL process, and may inspire the design of new CL architecture.

As one promising carbon-based material, sp³-hybrid carbon nitride has been predicted with various novel physicochemical properties. However, the synthesis of sp³-hybrid carbon nitride is still limited by the nanaoscale, low crystallinity, complex source, and expensive instruments. Herein, we have presented a facile approach to the sp³-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation. Actually, the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea, and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals. The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05% in solid state. The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially. Finally, the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage. This work paves new light on the synthesis strategy of sp³-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.

Recently, the chemiluminescence (CL) induced by carbon nanodots (CDs) has intrigued researchers’ extensive interests in various applications due to its special light emission principle. However, the difficulty of synthesizing chemiluminescent CDs with full-spectrum emission severely hinders the further regulation of the CL emission mechanism. Herein, the multi-color-emissive chemiluminescent CDs are rational designed and further synthesized by regulating the sp²-hybrid core and sp³-hybrid surface from the citrate-ammonia molecular in a single solvothermal reaction. More experimental characterizations and density functional theory calculations reveal that the higher temperature can promote the crosslinking polymerization/carbonization of carbon core and the higher protonation of solvent can determine the core size of final CDs, resulting in the variant CL emission from molecular-, crosslinking- and core-states. Thus, the CL emission of the CDs can be further synthesized by tuning the luminescence chromophores in the formation process via regulating the temperature and solvent, enabling the applications of the CL CDs in illumination and information encryption. This study paves a new technology to understand the luminescence of CDs and affords an industry translational potential over traditional chemiluminescent molecular.