Low-operational temperature for selective detection of xylene gas using a p-n CuO-ZnO heterostructure-based sensor

Xylene is not just considered detrimental to the environment but also hazardous to humans. Herein we report on xylene vapour detection using CuO-ZnO heterostructures containing various concentrations (0.1-2.0 wt%) of Zn, prepared via hydrothermal synthesis. X-ray diffraction, scanning, and transmission electron microscopy, as well as x-ray photoelectron spectroscopy, validated the formation of the CuO-ZnO heterostructure. Gas detection, sensitivity, selectivity, and stability tests of nine different gases, namely benzene, toluene, ethylbenzene, xylene, ethanol, methane, SO2, NO2, and CO2 at various operational tem-peratures were subsequently investigated. It was found that a CuO-ZnO heterostructure with 1.0 wt% Zn showed excellent selectivity towards 100 ppm of xylene at 100 & DEG;C. The sensor further demonstrated an insignificant cross-sensitivity (Sxylene/Stoluene=2.7) and (Sxylene/Sbenzene = 8.5) towards toluene and benzene vapour. Additionally, the ultra-low limit of detection of 9.5 ppb and sensitivity of 0.063 ppm-1 were ob-served towards xylene vapour, which indicated that the CuO-ZnO (1.0 wt%) heterostructure-based sensor can realize sub-ppb-level xylene concentration. The sensor disclosed excellent long-term stability in dry air and 40% relative humidity. The superior gas sensing characteristics could be ascribed to the superior surface area, the creation of p-n heterojunction, the robust chemical affinity, and the catalytic performance of p-type CuO on xylene vapour. The response mechanism towards xylene was also clarified.& COPY; 2023 Elsevier B.V. All rights reserved.