High surface area ZnO/rGO aerogel for sensitive and selective NO₂ detection at room temperature

Accurate and convenient detection of nitrogen dioxide (NO₂) in the air, which is harmful to human health, is vital. However, it is difficult for many NO₂ detection devices to achieve high sensitivity at room temperature. In this work, we synthesized zeolite-imidazolate-frameworks-8 (ZIF-8) nanoparticles and zinc oxide/reduced graphene oxide (ZnO/rGO) aerogel by low-temperature synthesis and sol-gel method. The aerogel composite materials were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Brunaue-Emmette-Teller (BET), and Raman spectroscopy. The gas-sensitive element prepared by the material with the mass ratio ZIF-8 to rGO is 5:1 possesses excellent selectivity and higher sensitivity (3.21) to 100 ppm NO₂ at room temperature. Reduced graphene oxide (rGO) provides more gas transmission and diffusion channels for improving sensitivity because of a three-dimensional porous structure. When NO₂ is exposed, electrons transfer into p-n heterostructure formed by rGO and ZnO composite to achieve the purpose of sense. In this study, the material preparation method is relatively simple and efficient, which is of profound significance to accurately detect the variation of NO₂ concentration in air at room temperature.