Room temperature NO2 sensing: what advantage does the rGO–NiO nanocomposite have over pristine NiO?

Abstract

In recent years, there has been increasing interest in synthesis of reduced graphene oxide (rGO)–metal oxide semiconductor (MOS) nanocomposites for room temperature gas sensing applications. Generally, the sensitivity of a MOS can be obviously enhanced by the incorporation of rGO. However, a lack of knowledge regarding how rGO can enhance gas-sensing performances of MOSs impedes its sensing applications. Herein, in order to get an insight into the sensing mechanism of rGO–MOS nanocomposites and further improve the sensing performances of NiO-based sensors at room temperature, an rGO–NiO nanocomposite was synthesized. Through a comparison study on room temperature NO₂ sensing of rGO–NiO and pristine NiO, an inverse gas-sensing behavior in different NO₂ concentration ranges was observed and the sensitivity of rGO–NiO was enhanced obviously in the high concentration range (7–60 ppm). Significantly, the stimulating effect of rGO on the recovery rate was confirmed by the sensing characteristics of rGO–NiO that was advantageous for the development of NO₂ sensors at room temperature. By comprehending the electronic interactions between the rGO–MOS nanocomposite and the target gas, this work may open up new possibilities for further improvement of graphene-based hybrid materials with even higher sensing performances.