The Effect of Doping rGO with Nanosized MnO2 on Its Gas Sensing Properties

Manganese dioxide (MnO2) has drawn attention as a sensitiser to be incorporated in graphene-based chemoresistive sensors thanks to its promising properties. In this regard, a rGO@MnO2 sensing material was prepared and deposited on two different substrates (silicon and Kapton). The effect of the substrate nature on the morphology and sensing behaviour of the rGO@MnO2 material was thoroughly analysed and reported. These sensors were exposed to different dilutions of NO2 ranging from 200 ppb to 1000 ppb under dry and humid conditions (25% RH and 70% RH) at room temperature. rGO@MnO2 deposited on Kapton showed the highest response of 6.6% towards 1 ppm of NO2 under dry conditions at RT. Other gases or vapours such as NH3, CO, ethanol, H2 and benzene were also tested. FESEM, HRTEM, Raman, XRD and ATR-IR were used to characterise the prepared sensors. The experimental results showed that the incorporation of nanosized MnO2 in the rGO material enhanced its response towards NO2. Moreover, this material also showed very good responses toward NH3 both under dry and humid conditions, with the rGO@MnO2 sensor on silicon showing the highest response of 18.5% towards 50 ppm of NH3 under 50% RH at RT. Finally, the synthetised layers showed no cross-responsiveness towards other toxic gases.