Effect of temperature and time on the exfoliation and de-oxygenation of graphite oxide by thermal reduction

The effect of thermal reduction temperature and time on the structure and composition change of reduced graphite oxide sheets was studied. The results show that the exfoliation degree increased with the elevation of temperature, as evidenced by the decreased layers in the defected nanocrystallites formed by the collapse of graphite oxide sheets. Although, the exfoliation degree shows reverse trend with the extension of time studied. As for the de-oxygenation, both the elevation of temperature and the extension of time favor the reduction process, evidenced by the increasing atomic ratio of carbon to oxygen, and a quite marked de-oxygenation effect was obtained with atomic ratio of 499 by heating at 1000 °C for 2 h. A structural schematic of thermally reduced graphite oxide sheets was proposed for the understanding of the reduction process.