Kinetic study of the graphite oxide reduction: Combined structural and gravimetric experiments under isothermal and nonisothermal conditions

Abstract

The mechanisms involved in the thermal reduction of graphite oxide (GO) are not yet clear. In the present study, the thermal reduction of GO, obtained by a Brodie-based method, is monitored by means of time- and temperature-resolved X-ray diffraction (XRD), thermogravimetric analysis (TGA), and TGA/mass spectrometry (MS) in dynamic (nonisothermal) and static (isothermal) modes. Two distinct mechanisms were well resolved by the fitting of isothermal TGA data to 2D diffusion and autocatalytic models, which provides new insights on the thermal behavior of GO. The combined TGA and XRD results in isothermal mode suggest that the 2D diffusion mechanism mainly occurs in the interlayer, whereas the autocatalytic mechanism occurs in the external surface. The latter overcomes the former when GO has lost about 10 wt %. The results are compared to previous studies on the thermal reduction of GO. The differences found could be attributed to the synthetic method used to obtain GO.