Precise tuning chemistry and tailoring defects of graphene oxide films by low energy ion beam irradiation

Precise tuning chemistry and tailoring nanopores of graphene oxide (GO) thin films are vital for their application for liquid and gas separation. In this work, ultra-thin GO films with thicknesses of about 150 nm were prepared and then modified by a low energy carbon ion beam with ion fluences ranging from 1 x 10(15) ions.cm(-2) to 1 x 10(17) ions.cm(-2). An ion fluence of 1 x 10(16) ions.cm(-2) is a threshold for the changes to the surface geometry (i.e. the chemical state and the consequent morphology) of the GO films. Moreover, X-ray photoelectron spectroscopy (XPS) reveals that oxygen loss in ion beam-induced reduction of GO films was mainly by the elimination of the unstable C=O species. Raman spectroscopy indicates that a mass of defects with a mean defect distance of about 1.4 nm was generated in GO films by C+ irradiation. According to SRIM simulation, an average of 208 carbon vacancies were created in the GO film per impinging C+. These results suggest that low energy carbon ion beam irradiation is promising for simultaneously reducing and drilling nanoscale pores on GO surfaces in a controllable manner, which could be used for engineering GO-based separation membranes.