Cross-Interference of VOCs in SnO2-Based NO Sensors

Abstract

In this work, we studied the influence of cross-interference effects between VOCs and NO on the performance of SnO2 and Pt-SnO2-based gas sensors. Sensing films were fabricated by screen printing. The results show that the response of the SnO2 sensors to NO under air is higher than that of Pt-SnO2, but the response to VOCs is lower than that of Pt-SnO2. The Pt-SnO2 sensor was significantly more responsive to VOCs in the NO background than in air. In the traditional single-component gas test, the pure SnO2 sensor showed good selectivity to VOCs and NO at 300 °C and 150 °C, respectively. Loading noble metal Pt improved the sensitivity to VOCs at high temperature, but also significantly increased the interference to NO sensitivity at low temperature. The explanation for this phenomenon is that the noble metal Pt can catalyze the reaction between NO and VOCs to generate more O−, which further promotes the adsorption of VOCs. Therefore, selectivity cannot be simply determined by single-component gas testing alone. Mutual interference between mixed gases needs to be taken into account.