NO₂ gas sensing performance enhancement based on reduced graphene oxide decorated V₂O₅ thin films

Abstract

Here, we demonstrate improved NO₂ gas sensing properties based on reduced graphene oxide (rGO) decorated V₂O₅ thin film. Excluding the DC sputtering grown V₂O₅ thin film, rGO was spread over V₂O₅ thin film by the drop cast method. The formation of several p-n heterojunctions was greatly affected by the current-voltage relation of the rGO-decorated V₂O₅ thin film due to the p-type and n-type nature of rGO and V₂O₅, respectively. Initially with rGO decoration on V₂O₅ thin film, current decreased in comparison to the pristine V₂O₅ thin film, whereas depositing rGO film on a glass substrate drastically increased current. Among all sensors, only the rGO-decorated V₂O₅ sensor revealed a maximum NO₂ gas sensing response for 100 ppm at 150 °C, and it achieved an approximately 61% higher response than the V₂O₅ sensor. The elaborate mechanism for an extremely high sensing response is attributed to the formation and modulation of p-n heterojunctions at the interface of rGO and V₂O₅. In addition, the presence of active sites like oxygenous functional groups on the rGO surface enhanced the sensing response. On that account, sensors based on rGO-decorated V₂O₅ thin film are highly suitable for the purpose of NO₂ gas sensing. They enable the timely detection of the gas, further protecting the ecosystem from its harmful effects.