Fast detection of NO2 by In2O3@ZnO nanofibers synthesized by coaxial electrospinning: Real-time monitoring application of smart mask

An efficient portable gas sensor was developed to meet the needs of air quality monitoring, for the detection of nitrogen dioxide (NO 2 ). In this study, coaxial electrospinning technology was used to synthesize porous nanofibers of indium oxide (In 2 O 3 ) composite zinc oxide (ZnO), which are recognized as special semiconductor ceramic materials. The best sample (NFs.1–6) consists of a nanoparticle-based structure with interconnected pores, in contrast to the more compact, tightly bonded nanofibers. This porous structure enhances gas adsorption capacity, improving the sensor’s performance. At 200 °C, the synthesized In 2 O 3 @ZnO (NFs.1–6) nanofibers exhibited a high response value of 171.25 and a fast response time of 5 s to 100 parts per million (ppm) NO 2 . The excellent characteristic is attributed to its uniform structure and n-n homojunction, making the response values 38 times and 98 times that of pure ZnO and pure In 2 O 3 , respectively. Building on the research findings, a smart mask was developed that incorporates the nanofiber sensor to monitor NO 2 concentrations in the air, offering an innovative approach to wearable gas sensor technology by semiconductor ceramic materials.