Fabrication of uniform monolayers of graphene oxide on solid surfaces

‘Soft matter’ strategies for the formation of thin films of graphene oxide (GO) and reduced GO may offer an alternative to the expensive vacuum deposition methods in fabricating solid-supported two-dimensional (2D) carbons (C). Herein, the authors describe a new method that exploits the transfer of GO monolayers from the oil/water interface onto various solids. By using a combination of spectroscopy, microscopy and contact angle method, the authors studied the effects of experimental parameters, such as the concentration of the GO dispersion, temperature and the chemistry of the solvent, on the lateral organization of the deposited GO monolayers. Temperature and concentration were shown to be the factors that control the smoothness and packing density of GO deposited on solids. The authors also demonstrate that the degree of reduction of GO by microwave heating correlates with the change in the surface energy of these films, which can be used to control the efficiency of the process. A two-step procedure comprising subsequent reduction and deposition of the monolayers was developed for fabrication of perfectly flat, densely packed arrangements. The authors believe that the results might be useful for the advancement of the colloidal approaches to new 2D carbon-based nanomaterials associated with various applications of thin films.