▎ 摘　　要

A well dispersed graphene aqueous solution was achieved by hydrothermal reduction method, in which graphene oxide (GO) was reduced by employing an effective reagent of hydrazine hydrate (N2H4 center dot H2O). The reduction degree of reduced graphene oxide (RGO) was preciously regulated via different reduction time. The obtained products were confirmed by X-ray diffraction, scanning and transmission electron microscopy, Fourier-transform infrared spectroscopy. The energy band gap of reduced graphene with different reaction time was characterized by ultraviolet-visible spectroscopy. The results showed that hydrothermal reduction method is a simple and efficient approach to synthesizing the dispersed graphene nanosheets aqueous solution, which is stable for several months without obvious precipitates or stratification in basic solvent. The energy band gap of different degree of reduction RGO can be tuned tremendously via controlling the reduction time.