Reduction of graphene oxide thin films using a stepwise thermal annealing assisted by L-ascorbic acid

Abstract

In this study, an environmental and economical multi-step reduction method has been developed for the reduction of graphene oxide thin films more efficiently. Within the scope of the method, the graphene oxide films produced were subjected to the process of chemical reduction with L-ascorbic acid (Vitamin C) as the first step and then to the process of thermal reduction that can be performed through progressive thermal annealing without any need for special atmospheric conditions as the second step. In addition, the impact of L-ascorbic acid solutions with different molarities (5, 25, 50, 100, 200, 400 and 800 mM) on the conductivity of the reduced graphene oxide produced was examined and compared with hydrazine hydrate for the same concentrations. Besides, the impact of different thermal annealing temperatures (70 degrees C, 120 degrees C and 300 degrees C) and the process of intermediate drying on the conductivity of the reduced graphene oxide thin films were investigated. The results show that the graphene oxide thin films were best reduced through 800 mM L-ascorbic acid and progressive thermal annealing combination (at 70 degrees C, 120 degrees C and 300 degrees C respectively) and that 13.2 k Omega/sq. surface resistivity was achieved and that the intermediate heating at 120 degrees C made at least 10% positive contribution to this.