New insights into the thermal reduction of graphene oxide: Impact of oxygen clustering

Graphene has attracted interest for a number of applications ranging from electronics, optoelectronics to membrane-based technologies. The thermal reduction of chemically exfoliated graphene oxide (GO) sheets represents an important step for large-scale, solution-based graphene synthesis. Therefore, understanding the reduction process and being able to provide new handles to control the resulting sheet properties is highly desirable. Using atomistic calculations combined with experiments, we study and demonstrate the impact of one such new handle e oxygen clustering on the graphene basal plane e on the structural and electrical properties of reduced GO (rGO) structures. Our calculations reveal that the number of oxygen and carbon atoms removed from the graphene plane during reduction can be tuned depending on the degree of oxygen clustering, without altering the reduction temperature. Further, we demonstrate that rGO thin films with improved sheet resistance (up to 2-fold smaller) can be obtained by facilitating oxygen clustering prior to reduction. Overall, our results highlight that oxygen clustering serves as a useful handle in controlling the structural and electrical properties of the resulting rGO structures, and could be potentially useful toward the synthesis of electrodes, graphene quantum dots and for different graphene-based thin film applications. © 2015 Elsevier Ltd. All rights reserved.