Cross-Linking Stabilizes Electrical Resistance of Reduced Graphene Oxide in Humid Environments

Reduced graphene oxide (rGO) is an excellent candidate for many sensor applications, since its electrical properties can be tailored to become sensitive to temperature, humidity, strain, and chemicals. However, the wide use of rGO may be limited by its susceptibility to humidity changes. Here, for the first time, we report experimental evidence that (i) the interlayer spacing between rGO sheets can swell upon exposure to humid environments due to the intercalation of water and (ii) the expanded interlayer spacing increases electrical resistance. As a novel means of mitigating this instability, ethylenediamine was used as a covalent cross-linker to anchor rGO sheets to limit interlayer expansion and stabilize electrical resistance under humid environments.