Evidence of Ion-Beam-Induced Annealing in Graphene Oxide Films Using in Situ X-Ray Diffraction and Spectroscopy Techniques

Abstract

Ion beam irradiation is one of the methods to tune the properties of graphene oxide (GO) by modifying the ratio of sp2 and sp3 hybridization. However, the inherent defects present in GO during its synthesis deteriorate its properties (e.g., reduction efficiency) and are difficult to remove. We have earlier demonstrated the annealing of defects in carbon nanostructures (fullerene, carbon nanotube, and graphene) at a lower fluence of swift heavy ion (SHI) irradiation. In the present work, we have studied the irradiation of the GO film with 120 MeV Au ions at fluences ranging from 1010 to 1013 ions/cm2. In situ X-ray diffraction measurements showed an increase in the crystallinity of the GO film at low fluence. The irradiated samples showed an increase in the intensity of aromatic carbon bonds by Fourier transform infrared spectroscopy which indicates the maximization of graphitic regions for lower fluences up to 3 × 1011 ions/cm2. Higher fluences of ion beam irradiation indicated the loss in crystallinity and presence of carbyne in Raman measurements. Thermal spike simulations were performed to understand the physical processes involved during ion beam irradiation by estimating the radii of core and halo of the tracks formed by SHI.