Supercritical alcohols as solvents and reducing agents for the synthesis of reduced graphene oxide

Abstract

We report on a facile, simple, and green graphene oxide (GO) reduction method based on a supercritical alcohol approach. The influence over the chemical, thermal, morphological, and textural properties of reduced graphene oxides (RGOs) of five different alcohols in their supercritical conditions - methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol - was investigated in detail. Although the thermal stabilities and Fourier-transform infrared spectra of RGOs produced using the different alcohols are very similar, a substantial difference in the carbon-to-oxygen ratios measured by X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller surface areas are observed. The RGO produced using supercritical ethanol exhibited a much higher carbon-to-oxygen ratio of 14.4 and a much larger surface area of 203 m(2)/g compared with that produced using the other supercritical alcohols. Raman spectra showed that the RGOs produced using supercritical ethanol and supercritical 2-propanol retained more of the graphitic structure. X-ray diffraction analysis revealed that RGOs produced using supercritical 1-propanol and supercritical 1-butanol retained at least two different interlayer spacings. The deoxygenation mechanism of GO in supercritical ethanol is proposed based on gas and liquid product analysis. Crown Copyright (C) 2013 Published by Elsevier Ltd. AU rights reserved.