Apparent Roughness as Indicator of (Local) Deoxygenation of Graphene Oxide

Abstract

Detailed characterization of graphene oxide (GO) and its reduced forms continues to be a challenge. We have employed scanning tunneling microscopy (STM) to examine GO samples with varying degrees of deoxygenation via controlled chemical reduction. Analysis of the roughness of the apparent height in STM topography measurements, i.e. the “apparent roughness”, revealed a correlation between increasing deoxygenation and decreasing apparent roughness. This analysis can therefore be a useful supplement to the techniques currently available for the study of GO and related materials. The presence of a high electric field underneath the STM tip can locally induce a reaction on the GO basal plane that leads to local deoxygenation, and the restoration of the sp2 hybridization of the carbons promotes increased planarity. These findings are in line with the apparent roughness values found for GO at varying levels of chemical reduction and illustrates the value of having a tool to gain structural/chemical insight on a ...