Graphite oxide (GO) is convenient to be used as a precursor for functionalization studies and explore the chemistry in solution. Since GO is solution-processable and hygroscopic, tuning the chemical properties by reduction therefore tailors the electronic and electric properties of thermally/chemically reduced GO. The reduction processes of GO sheets have gained much interest since improvement and systematic investigation of the graphitic structure-electrical property relationship is particularly required for graphene nanoelectronics applications. The excellent electrical conductivity of the reduced GO sheets therefore promises potential electronic applications.

 

It was reported by Su et al. in (ACS Nano, 4, 5285-5292, 2010) that the use of high-temperature alcohol vapor for reducing GO increases the conductivity dramatically which improves the graphitic domains. However, details of understanding reduction mechanisms behind the interactions of alcohol molecules within the reduced defective sites of reduced GO still remains elusive.

 

One of our recent study in (ACS Nano 4, 5861-5868, 2010) shows that trapped water molecules intercalate in the interlayers of as-synthesized GO and interacts with the carbon dangling bonds of the etch holes upon reduction. In this study, formation of carbonyl groups and production of CO2from the structural decomposition is a key experimental observation. Replacing intercalated water with methanol and ethanol and performing thermal reduction of GO at 60-300°C, in-situ infrared spectroscopy measurements in transmission demonstrate that the thermal reduction efficiency of reduced GO changes dramatically within two different alcohol environment. In the presence of methanol in the interlayers of reduced GO, an increase of infrared absorption could be observed which is attributed to a stable carbonyl concentration during annealing. In contrast, compared with methanol, carbonyl formation at ~1750-1850 cm-1 is absent when there is ethanol in the interlayers of reduced GO. To understand differences in these experimental observations, we simulate the reduction mechanisms by both MD and DFT calculations which show a faster diffusion of methanol in the interlayer of GO that facilitate its reaction with etch holes, inducing a competing mechanism. In the case of ethanol intercalation, simulations confirm that the carbonyl formation which tends to enlarge the etch hole upon annealing can be blocked.