▎ 摘　　要

Graphene oxide( GO ) sheets were cut into smaller pieces in water by ultrasonic. The effects of treatment time on the GO sheets' size and GO surface groups were investigated. Moreover, the mechanism of cutting process was discussed. The results indicate that the diameter of GO sheets decreases from 2000 nm to 200 nm with increasing treatment time. The species of GO surface groups do not change after ultrasonic treat. ment. However, with increasing treatment time, the content of epoxy groups decreases, the content of carbox-ylate groups changes little, the content of ketone groups firstly decreases and then increases, the content of hy. droxyl groups firstly increases and then decreases, and the content of ether oxygen groups increases. The ultra. sonic cavitation leads to the break of carbon. carbon bonds, epoxy groups and ketone groups, which fractures the GO sheets. After that, the hydroxyl radical and hydrogen radicals formed from water react with carbon radi. cals of GO to form new carbon. carbon bonds and ether oxide or hydroxyl groups. The hydroxyl groups convert into ketone groups under long time ultrasonic treatment. The cutting process of GO by ultrasonic can be procee. ded under mild conditions without other chemicals, which is a promising technology for cutting two. dimension. al materials.