Engineering of structural and surface functional characteristics of graphite oxide nanosheets by controlling oxidation temperature

The specific application potential of graphite-based materials mostly depends on their structural and surface properties and hence their synthetic conditions. Among the graphite family, graphite oxide (GO) nanosheets have demonstrated applications in fields such as ionic conductor, sensor and nano-electronic structural support. We have developed a general strategy to control the surface functional groups namely carboxyl, carbonyl, epoxy and hydroxyl groups present on the GO by varying the oxidation temperature from 30 to 110 degrees C using the modified Hummer's method. Analytical investigations suggested that the best condition for synthesizing GO was found to be about 50 degrees C based on the crystallinity and its single sheet nature. Interestingly, the concentration of the functional groups on the surface of GO nanosheets increases with the oxidation temperature until 50 degrees C and decreases thereafter, possibly due to the condensation reaction between the epoxy and the hydroxyl groups. The temperature dependent change in the properties is well explained in terms of the change in the functional groups present on the surface of the GO. This study has a high impact not only for changing properties of GO but also towards the designing of electronic devices and sensors.