Development of a Conductometric Sensor Based on Al,Ca-Doped ZnO for the Detection of Formaldehyde

Abstract

In the present study, the development of a conductometric gas sensor based on Al,Ca-doped zinc oxide composite which is finalized to the detection of formaldehyde (HCHO) at a low concentration in air is investigated. The electrical and sensing properties of the composite based on ZnO doped with different loadings of Al and/or Ca (from 0 up to 5 at%) were evaluated. The gas-sensing mechanism of Al,Ca-doped zinc oxide nanocomposite-based sensors was also discussed. The optimized 3%Al,3%Ca-ZnO sensor displayed a formaldehyde response of 3.5 (@ 4 ppm HCHO/air) and an experimental low detection limit of 125 ppb HCHO/air, at the operating temperature of 400 °C. The sensor was also shown to be selective to HCHO with respect to many interferent indoor gases, but NO2 changed the baseline resistance in an opposite way compared to the target gas. The developed device for monitoring HCHO in indoor and workplace environments has the advantage of a simple planar structure and can be easily fabricated for mass production by using low-cost materials and easy fabrication methods.

Ammonia gas sensors based on undoped and Ca-doped ZnO nanoparticles

“…In addition, the sharp peaks at 650 cm −1 and 870 cm −1 correspond to Zn–O stretching vibrations, which is a characteristic feature of ZnO. 33 When calcium is doped into the ZnO lattice, changes in the intensity of the O–H stretching peak around 3200–3700 cm −1 were noted. The increase in the intensity suggests an increase in the concentration of O–H groups, likely due to the dopant calcium ions, which promote the adsorption of water.…”

Preparation of ZnO Thick Films Activated with UV-LED for Efficient H2S Gas Sensing

“…The latter, ZnO, is a material obtained through simple methods, and its manufacturing is low cost. It is an n-type semiconductor with a bandgap of ~3.37 eV, an exciton binding energy of 60 meV, and high electron mobility of 400 cm 2 V −1 s −1 [9]. It exhibits transparency in the visible spectrum and high reflectivity in the infrared region [10].…”

Facile Mesoporous Hollow Silica Synthesis for Formaldehyde Adsorption

“…However, in 2004, formaldehyde was classified as a potential carcinogen and teratogen by the World Health Organization (WHO). In particular, formaldehyde emitted from wooden or leather furniture in an indoor environment can have serious adverse effects on human health [ 4 , 5 , 6 ]. The International Agency for Research on Cancer (IARC) under the WHO has classified formaldehyde as a class one carcinogen that can cause fatal damage to organs such as the liver, kidney, eyes, nose, skin, and throat.…”