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Miniaturized low-cost sensors for volatile organic compounds (VOCs) have the potentiality to become a fundamental tool for indoor and outdoor air quality monitoring, to significantly improve everyday life. Layered double hydroxides (LDHs) belong to the class of anionic clays and are largely employed for NO x detection, while few results are reported on VOCs. In this work, a novel LDH coprecipitation method is proposed. For the first time, a study comparing four LDHs (ZnAl−Cl, ZnFe−Cl, ZnAl− NO 3 , and MgAl−NO 3 ) is carried out to investigate the sensing performances. As explored through several microscopy and spectroscopy analyses, LDHs show a morphology characterized by a large surface area and a three-dimensional hierarchical flowerlike architecture with micro-and nanopores that induce a fast diffusion and highly effective surface interaction of the target gases. The fabricated sensors, operating at room temperature, are able to reversibly and selectively detect acetone, ethanol, ammonia, and chlorine vapors, reaching significant sensing response values up to 6% at 21 °C. The results demonstrate that by changing the LDHs' composition, it is possible to modulate the sensitivity and selectivity of the sensor, helping the discrimination of different analytes, and the consequent integration on a sensor array paves the way for electronic nose development.

A new flexible polymeric gas sensor is developed by photocrosslinking poly(ethylene glycol) diacrylate resin (PEGDA) containing multi‐walled carbon nanotubes (MWCNTs) as conductive filler. The cured material shows a percolative threshold conductivity which changes when in contact with various gas analytes with different chemical and physical properties. The different behavior of the sensors toward the different gases is explained either on the basis of chemical affinity toward the polymeric matrix or due to the interactions that can occur between the analyte and the surface of the nanotubes in the case of the aromatic gas.

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