FexZn1-xOy as room temperature dual sensor for formaldehyde and ammonia gas detection

Abstract

The present research centres on synthesizing Zinc Oxide (ZnO) nanostructures with exceptional surface modification via Iron (Fe) doping (2–8%) using the sol-gel route. The as-synthesized samples were analyzed to scrutinize the structural, morphological, optical and gas sensing attributes of ZnO and Iron doped ZnO (Fe-ZnO). The investigation discloses appreciable sensing performance for different volatile organic compounds(VOCs), exclusively for Ammonia (NH3) and Formaldehyde (HCHO) gases. The X-ray diffraction pattern revealed a well hexagonal wurtzite structure and slight (1 0 1) preferred orientation growth. The crystallite size was increased from 13.43 nm to 14.93 nm by increasing the doping level of Fe in ZnO. Moreover, gas sensor studies of ZnO and Fe doped ZnO nanomaterials synthesized at various doping amounts were tested at room temperatures and at different NH3 and HCHO gas concentrations. The sensor response for the 8% Fe doped ZnO sample was observed as 305 and 83, whereas response and recovery time were (1.71 s, 2.06 s) and (1.6 s, 1.23 s) for NH3 and HCHO, respectively, at room temperature. For 100 ppm NH3 and HCHO concentration, ZnO, Fe-ZnO (2%), Fe-ZnO (4%), Fe-ZnO (6%), Fe-ZnO (8%) gas sensors displayed gas responses of 8688.03, 1426, 2426.92, 5893.76, 27173.22 and 60.25, 268.22, 369.70, 2560.92, 34105.16 respectively. Hence, 8% Fe-doped ZnO sensor displayed appreciable response and low response and recovery time than sensors based on pure and Fe doped NiO with dopant concentration 2–6%.