Controllable O2•− oxidization graphene in TiO2/graphene composite and its effect on photocatalytic hydrogen evolution

► The O2
- −, which generated from the reaction of photoinduced electrons and O2 can increase the oxygen groups on graphene planar in TiO2/graphene composite at ambient condition. ► This O2
- − oxidation is moderate and controllable. ► Moderate oxidized graphene by O2
- − can significantly promote the photocatalytic hydrogen evolution performance of the TiO2/graphene composite.