Low-cost route for top-down synthesis of over- and low-oxidized graphene oxide

An essential requirement for the mass production of graphene oxide materials is to keep the low-cost potential. The present study demonstrates the low-cost-route for the synthesis of over- and low- oxidized graphene oxide. A simplified Hummers method for the synthesis of graphene oxide (GO), without the use of NaNO3 and/or H3PO4, was applied using graphite flakes with unordered large size (75 % over 150 iim). The inexistence of toxic gasses (NO2/N2O4) and soluble ions (Na+/NO3-) preserved the environmental duty of GO production. The low-oxidized graphene oxide (rGO) produced after a short thermal process in vacuum. The low energy consumption (250 degrees C for 1 h) and the absence of additive agents (as argon or nitrogen gas) minimized the whole synthesis cost. The over- and low- oxidized GO characterized with scanning electronic microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD), energy dispersive X-ray spectroscopy (EDS), attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR), N-2 porosimetry, and UV-vis spectrophotometry. The over-oxidized GO presented high specific surface area (similar to 72m(2) /g) and carbon content similar to 45 %. The low-oxidized GO had carbon content similar to 80 % and embodied to chitosan-based composites. Some possible industrial-scale applications of the products are suggested.