CeO2-filter-based monolithic bilayer gas sensors for selective, sensitive, and fast methanol detection

초록

Sensitive and selective detection of methanol, an extremely toxic chemical, is critical for ensuring public health and safety because of its widespread use in industrial applications. However, real-time and on-site monitoring of methanol remains challenging, because of comparable sensor responses to both methanol and ethanol/formaldehyde. In this paper, we present a monolithic bilayer gas sensor with a catalytic CeO2 filter for the sensitive and selective detection of methanol. The sensor exhibited high response (resistance ratio = 3.5), selectivity (response ratio > 16.8), a low detection limit (0.021 ppm), and fast sensing kinetics (response speed: 4.0 s), which were maintained even in gas mixtures. The mechanism underlying the selective and sensitive detection was investigated in relation to the synergistic effects of inhibiting methanol conversion while promoting its transformation into highly reactive acetaldehyde, which was confirmed by the analysis using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). We investigated the performance of the sensor with respect to the thickness and configuration of the CeO2 overlayer. Moreover, the sensor arrays proved efficient in discriminating methanol from various interferents (ethanol, formaldehyde, acetone, carbon monoxide, and ammonia). Therefore, this study provides fresh insights into the design of highly precise, reliable, and cost-effective methanol sensors.

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