Microwave-Assisted Confining Growth and Liquid Exfoliation of sp3-Hybrid Carbon Nitride Nano/Micro-Crystals

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.