Abstract：Ultrasonic synthesis of carbon dots has broad application prospects because of its simple process, low cost and less secondary pollution. To optimize the technological parameters of ultrasonic synthesis, carbon dots samples were prepared with different critical process parameters. Emission and excitation spectra were measured, and the effects of quantum dot concentration, types of solvent, auxiliary agent type and concentration, and ultrasonic power and time on luminescence properties of carbon dots were analyzed. The results showed that carbon dots prepared by ultrasonic had a excitation wavelength dependence, and their emission peaks significantly changed with the excitation wavelengths. When carbon dots concentrations increased, their Luminous intensities first increased and then decreased because of the radiation energy transfers and quantum dots reunion. Due to solvent effect, luminous intensities of carbon dots in ethanol were stronger than that in water, and wavelengths of carbon dots in ethanol were shorter than that in water. And the greater the concentrations of carbon dots were, the more obvious the wavelengths of emission spectra moved. Compared with hydrochloric acid, carbon dots prepared with sodium hydroxide as adjuvant had a better surface passivation and stronger luminous intensities. Besides, surface passivation of carbon dots could be improved by increasing the NaOH concentration, and much more carbon dots could be obtained by increasing ultrasonic power or time appropriately, but if the ultrasonic time was too long, carbon dots were prone to reunite quenching. The above analysis of influencing factors provides a theoretical basis for parameter optimization of carbon quantum dots prepared by ultrasonic, which is conducive to the mass production and application of carbon quantum dots at a low cost.
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