Gas Sensing Properties of Functionalized Graphene Oxide

Abstract

Graphene oxide (GO), an atomically thin layer of graphite decorated with oxygen containing functional groups, is one of the leading candidate materials for high-performance gas sensing operating at room temperature. It is well known that defects on the surface of GO, including oxygen functional groups, can act as active sites for interaction with molecules, enhancing the sensitivity of the gas sensors. However, the role of functional groups in graphene oxide for gas sensing has not been reported yet. In this study, gas sensing properties of GO focusing on the role of its functional groups are studied. First, the role of oxygen functional groups in NO2 sensing is demonstrated by investigating the sensing behavior of GO and reduced GO (rGO) sensors with different degree of reduction. The response and recovery ratio are increased with increase in the amount of oxygen functional groups. First-principle calculations reveal the critical role of hydroxyl functional groups in the molecular sensing. One of the biggest challenges in gas sensors is generating selectivity. Here, we also demonstrate that GO sensor shows different gas sensing properties depending on the kind of functional groups. The oxygen functional gorups in GO sensor were changed to fluorine containing groups using facile and scalable method. The rGO sensor gives higher response to NO2 than that of fluorinated GO (F-GO). For NH3 sensing, however, the response of F-GO sensor is about 4 times as great as that of rGO sensor. We expect that developments of highly selective and sensitive gas sensors are feasible by controlling functionalization of GO.