Preparation of exfoliated graphite intercalated with nitrogen dioxide by direct gas-phase processing

Graphite intercalation compound (GIC) as a precursor of exfoliated graphite (EG) was easily prepared by direct reaction of nitrogen dioxide gas with natural flake graphite (NFG). This preparation involved a one-step method under optimum conditions of 55 degrees C and 0.45 MPa for 48 h in a dry, sealed steel container. The maximum exfoliation volume (EV) of EG was up to 240 ml g(-1) with the exfoliated method at 1000 degrees C. A comparative study of properties and microstructure distinctions between GIC and EG samples was carried out using scanning electron microscopy, thermal gravity analysis, and differential scanning calorimetry coupled with Fourier transform infrared spectroscopy. The influence of reaction condition on the property, structure, and EV of the EG was also discussed. (C) 2014 Elsevier B.V. All rights reserved.