H2O2-free strategy derived from Hummers method for preparing graphene oxide with high oxidation degree

Hydrogen peroxide (H 2 O 2 ) is required to reduce the residual potassium permanganate (KMnO 4 ) 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 (H 2 SO 4 ) to prepare high quality GO without H 2 O 2 , avoiding the high risk of the dramatically exothermic reduction reaction caused by the quenching reaction of adding H 2 O 2 . Notably, the C/O ratio of GO prepared by this H 2 O 2 -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.