▎ 摘　　要

Hydrogen peroxide (H2O2) is required to reduce the residual potassium permanganate (KMnO4) in the traditional Hummers method for preparing graphene oxide (GO), which is dangerous and uncontrollable. In this work, spontaneous-reduction of high-valence Mn ions is induced by simply adjusting the reaction temperature/time and the dosage of concentrated sulfuric acid (H2SO4) to prepare high quality GO without H2O2, avoiding the high risk of the dramatically exothermic reduction reaction caused by the quenching reaction of adding H2O2. Notably, the C/O ratio of GO prepared by this H2O2-free method is 1.986, which is less than commercial GO. Herein, this work provides a novel and efficient strategy for the safe and environmentally-friendly preparation of GO with high quality.