Low-temperature and high-response NO2 sensor based on oxygen vacancy-enriched ZnO tubes inherited from waste chestnut mesocarps

Abstract

Herein, we reported a low-cost ZnO biomorphic material used for low-temperature and high sensing detection of trace NO2. It was simply prepared by calcining Zn(NO3)2 solution soaked waste chestnut mesocarp biotemplate at 600 °C in air for the first time. The morphology of ZnO-6 material displays one-dimensional (1D) tubular structure assembled from uniform nanoparticles, and it has small mesopore distribution, relatively large specific surface area and abundant oxygen vacancy defects. The synergy of above advantageous factors provides a convenient channel for gas diffusion, and increases the surface active sites for adsorption and chemical reactions, which in turn efficiently enhances sensing performance of ZnO material towards NO2. At 92 °C, ZnO-6 sensor achieves a high response of 365 towards 10 ppm NO2, which is 30.4 times than that (S = 12) of template-free ZnO-0 sample. Also, it is larger than most reported 1D ZnO-based NO2 sensors. This sensor still possesses fast recovery characteristic, low detection limit, and good moisture tolerance. Moreover, the improved NO2 gas-sensing mechanism is discussed in more detail.