Local conductivity of graphene oxide study by conductive atomic force microscope

Abstract

In this paper, a Conductive Atomic Force Microscope was used to measure the current distribution image of monolayer graphene oxide (GO) and I/V curves of different types of points in current distribution. Graphene oxide (GO) was prepared by a modified Hummer's method and deposited on highly oriented pyrolytic graphite. We gradually increase the voltage range and analyze the effect of different voltages on improving the local conductivity of graphene oxide. It has been found that there are several critical voltages, such as 0.8 V, 1.5 V, 2.2 V, and 3.2 V. There is no current when the voltage is lower than 0.8 V; if the voltage is 1.5-2.1 V, the conductivity of GO can be slightly improved, but if not, it will significantly change the structure of graphene oxide; if the voltage is 2.2-3.1 V, the conductivity of GO can be greatly improved, but it still exhibits semiconductor properties; when the voltage increases to 3.2 V, the local conductivity of GO changes, showing metallicity. It was concluded that the strong electric field strength caused by voltage destroys the bond between oxygen-containing functional groups and the graphene oxide skeleton, which is very advantageous for studying the conductivity of GO.