Enhanced detection of low concentration volatile organic compounds using advanced doped zinc oxide sensors

Majdi Benamara; Ahmadou Ly; Sonia Soltani; Manel Essid; Hassen Dahman; Ramzi Dhahri; Lassaad El Mir; Marc Debliquy; Driss Lahem

doi:10.1039/d3ra03143h

Enhanced detection of low concentration volatile organic compounds using advanced doped zinc oxide sensors

RSC Adv. 2023 Oct 17;13(43):30230-30242. doi: 10.1039/d3ra03143h. eCollection 2023 Oct 11.

Authors

Majdi Benamara^{1

2}, Ahmadou Ly³, Sonia Soltani⁴, Manel Essid⁵, Hassen Dahman¹, Ramzi Dhahri⁶, Lassaad El Mir¹, Marc Debliquy⁷, Driss Lahem³

Affiliations

¹ Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE), Faculty of Sciences in Gabes, Gabes University 6072 Gabes Tunisia majdibenamara1@gmail.com.
² Laboratory for Building Energy Materials and Components, Swiss Federal Laboratories for Materials Science and Technology (Empa) Überlandstrasse 129 8600 Dübendorf Switzerland.
³ Service de Sciences des Matériaux, Université de Mons Rue de l'Epargne 56 7000 Mons Belgium.
⁴ Department of Physics, College of Science and Arts, Qassim University Dariyah 58251 Saudi Arabia.
⁵ Department of Chemistry, College of Science, King Khalid University Abha 61413 Saudi Arabia.
⁶ Department of Physics, Faculty of Sciences and Arts, Najran University P. O. Box 1988 Najran 11001 Saudi Arabia.
⁷ Materia Nova, Materials R&D Centre Parc Initialis, Avenue Nicolas Copernic 3 7000 Mons Belgium.

Abstract

Pure zinc oxide nanoparticles, as well as those doped with 3% calcium, aluminum, and gallium, were synthesized using a sol-gel method and then deposited onto an alumina substrate for sensing tests. The resulting nanoparticles were characterized using a variety of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), UV-VIS-NIR absorption spectroscopy, and photoluminescence (PL) measurements, to examine their structural, morphological, and optical properties. The prepared nanoparticles were found to have the hexagonal wurtzite structure of ZnO with a P63mC space group. The UV-Vis-IR spectra showed that the samples are highly absorbent in the UV range, while the PL spectra confirmed the presence of many defects in the ZnO structure, such as oxygen vacancies and zinc interstitials. The doped samples exhibited more defects than the pure sample. SEM images of the deposited film surface showed agglomerates with a spherical shape and confirmed the nanometer scale size of our prepared samples, as corroborated by the TEM images. The EDX spectra indicated the high purity of the ZnO deposited films, with a high presence of Zn and O and the presence of the doped elements (Ca, Al, and Ga) in each doped sample. Sensing tests were performed on ZnO, Ca_3%-doped ZnO (C3ZO), Al_3%-doped ZnO (A3ZO), and Ga_3%-doped ZnO (G3ZO) sensors in the presence of volatile organic compounds (VOCs) gases such as ethanol, formaldehyde, methanol, and acetone at low concentrations. The sensors exhibited high responses to low ppm level concentrations of the VOCs gases. At a low operational temperature of 250 °C, the C3ZO sensor had the highest response to 5 ppm of ethanol, methanol, and formaldehyde gases compared to the pure and other doped sensors. Additionally, the A3ZO sensor exhibited the highest response to acetone gas. In conclusion, our findings suggest that the doping of zinc oxide can enhance the low concentration detection of VOCs gases, with the C3ZO and A3ZO sensors showing the highest response to specific gases.