▎ 摘　　要

NOVELTY - The preparation method of carbon quantum dot involves adding graphene or carbon nanotubes to 10-25 mol/l nitric acid solution in ratio of 50-500 mg:100-300 ml, stirring, heating, refluxing and reacting for 0.5-5 hours to obtain mixed solution, then adding 0.5 %mass 12-120 mol/l sodium bicarbonate solution, ultrasonically processing at 40-80 degrees C and ultrasonic power of 100-300 W for 3 hours, then naturally cooling to room temperature, filtering using a microfiltration membrane having aperture of 0.1-0.5 mu m to obtain filtrate, centrifuging, evaporating supernatant to dryness, ten adding superpure water and stirring. USE - The method is useful for preparing carbon quantum dot. ADVANTAGE - The method enables simple preparation of carbon quantum dot with excellent solubility, strength and stability in an environmentally-friendly manner.