Detailed Investigation into the Preparation of Graphene Oxide by Dichromate Oxidation

Abstract

AbstractGraphene oxide (GO) can be prepared using numerous protocols including the well‐known Hummers method that relies on potassium permanganate as the oxidizing agent. Given the widespread use of GO and its many applications, a better understanding of the mechanisms of chemical oxidation is highly desirable including research into alternative oxidizing agents. Limited work has so far been carried out into using potassium dichromate as an oxidizing agent and the chemical structure of GO prepared by dichromate oxidation remains unclear. Here we present a full structural characterization of GO prepared by dichromate oxidation and we investigate its thermal stability. Furthermore, the previously reported preparation protocol is optimized by reducing the reaction time from 5 days to 20 hours and showing that sodium nitrate is not needed in the reaction mixture. Contrary to previous reports, we show that the GO material produced by dichromate oxidation is highly oxidized if thermal annealing is avoided. Compared to traditional GO, larger amounts of carboxylic acid groups are found which constitutes a major advantage for chemical processing and applications in materials chemistry.