The Effect of Doping rGO with Nanosized MnO[sub.2] on Its Gas Sensing Properties

Manganese dioxide (MnO[sub.2]) has drawn attention as a sensitiser to be incorporated in graphene-based chemoresistive sensors thanks to its promising properties. In this regard, a rGO@MnO[sub.2] 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@MnO[sub.2] material was thoroughly analysed and reported. These sensors were exposed to different dilutions of NO[sub.2] ranging from 200 ppb to 1000 ppb under dry and humid conditions (25% RH and 70% RH) at room temperature. rGO@MnO[sub.2] deposited on Kapton showed the highest response of 6.6% towards 1 ppm of NO[sub.2] under dry conditions at RT. Other gases or vapours such as NH[sub.3], CO, ethanol, H[sub.2] 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 MnO[sub.2] in the rGO material enhanced its response towards NO[sub.2]. Moreover, this material also showed very good responses toward NH[sub.3] both under dry and humid conditions, with the rGO@MnO[sub.2] sensor on silicon showing the highest response of 18.5% towards 50 ppm of NH[sub.3] under 50% RH at RT. Finally, the synthetised layers showed no cross-responsiveness towards other toxic gases.