Surface modification of ET-10 graphite by helium irradiation and preoxidation: Morphology, microstructure and chemical states

•Preoxidation and irradiation alter the morphology, structure and chemical state.•|q−1|and ID1/(ID1+ID2) reflect the variation in defect and crystallite size.•A low dose of irradiation is sufficient to effectively reduce the oxidised graphite.•Irradiation reduction is possibly related to the electron stopping power.