Structure and Property Evolution of Graphene Oxide Sheets during Low-Temperature Reduction on a Solid Substrate

Abstract

The structure and property evolution of graphene oxide (GO) during low-temperature (≤200 °C) reduction is related to the economically effective production and many behaviors of graphene-based materials, such as property tuning and long-term stability at high working temperatures. The interfacial effects on the physiochemical processes are yet to be quantified experimentally. Here, combining scanning polarization force microscopy with UV–vis absorption spectra, the formation and expansion of sp2 domains on individual single-layered GO sheets and the opto-electronic behaviors of GO films on average at low temperatures are in situ monitored. Kinetics of the interfacial evolutions are examined. Surprisingly, unexpected faster evolution of GO sheets at interfaces than that in bulk water is observed. We find this discrepancy can be addressed if the water atmosphere is taken into account and the humidity dependence of evolution is verified. Environmental water and asymmetric moisturizing of GO are believed to play important roles in the process. Based on this, the evolution rate is modulated via adjusting the humidity. The findings shed light on the interfacial structure and property evolution processes of GO and open a new avenue to manipulate the evolution rates at low temperatures.