Tailoring the oxygen content of graphene oxide by IR laser irradiation

Abstract

Graphene oxide (GO) foils, synthesized with the Hummers’ method, were IR laser treated in air and under vacuum at some laser fluences (300 and 600 mJ/cm2 in air and 200 mJ/cm2 under vacuum). Depending on the laser fluence and the used environment, it was possible to control the oxidation or reduction degree of GO foils. The evolution of the structural and compositional characteristics of the as-prepared GO films was examined through different physical characterization techniques. In particular, scanning electron microscopy (SEM), surface profilometry, energy-dispersive X-ray spectroscopy (EDX), Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) were used. A preliminary Raman analysis was also carried out on some GO foils. The results suggest the gradual restoration of sp2 clusters within the sp3 matrix under vacuum or in air at high laser fluences. In these conditions, the partial reestablishment of planarity and an increase in the D/G intensity ratio are also observed. In air, at low laser fluences, the IR laser irradiation causes GO films oxidation, increase in roughness and greater exfoliation availability. The useful deduced information about morphology and composition make the IR laser treatment a simple method for controlling the physical properties of GO film by tailoring the oxygen functional groups, and consequently, for the production of tailor-made highly conductive and defect-free graphene-like materials or GO composites with metals and organic molecules or GO doped with heteroatoms.