Structural, functional and magnetic ordering modifications in graphene oxide and graphite by 100 MeV gold ion irradiation

The modifications induced by 100 MeV gold ion beam irradiation on the structural, functional and magnetic properties of graphene oxide (GO) and graphite were studied. The local electronic structure of pristine GO was explained by C K-edge and O K-edge X ray absorption spectroscopy (XAS). The changes in electronic structure, elemental composition and structural disorder in pre and post irradiated samples were investigated using X ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The X ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FT-IR) exhibited the formation of GO and reduced graphene oxide (rGO) mixed state upon Au ion irradiation. Increase in disorder was observed from pristine GO (I-D/I-G similar to 3.22) to irradiated GO at ion fluence of 5 x 10(12)ions/cm(2) (I-D/I-G similar to 3.58) in Raman study. Increased carbon/oxygen ratio (C/O similar to 80.29%) and enhanced graphitization for GO was observed at fluence of 5 x 10(12) ions/cm(2). A decrease in C/O ratio (similar to 33.28%) was noticed in graphite upon Au ion irradiation at ion fluence of 7.5 x 10(12) ions/cm(2). The results are also supported by electron paramagnetic resonance (EPR) studies. The activation of localized spin states in graphite by ion irradiation was observed. The work demonstrates Au ion irradiation induced controlled reduction of GO and activation of magnetic order in graphite.