Selective and rapid detection of acetone using aluminum-doped zno-based sensors

Abstract

We report the preparation and characterization of pure and doped ZnO nanoparticles with 1%, 3%, and 5% aluminum (AZO) using a sol-gel method followed by annealing at 400 °C for 2 h. The structural and morphological properties of the AZO nanoparticles were analyzed using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) techniques, and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectrometry (EDS). Optical and specific area properties were investigated by photoluminescence (PL) and N2 physisorption measurements. The results showed that pure and doped AZO nanoparticles crystallize under a hexagonal wurtzite structure and exhibit spherical shapes with nanometric dimensions. TEM and SEM images revealed that the pure and Al-doped ZnO were round nanoparticles with a size smaller that 100 nm. FTIR measurements were conducted to investigate the presence of Al-O stretching vibrations, which served as an indication of aluminum incorporation into the ZnO lattice. The results confirmed the successful integration of aluminum into the ZnO structure. Additionally, XPS measurements were performed to examine the elemental composition of the AZO samples. The presence of Zn 2p peaks in all AZO samples, along with the presence of Al 2p peaks in the Al-doped ZnO structures, provided further evidence for the successful incorporation of Al ions into the ZnO lattice. The PL spectra revealed the presence of various defects (oxygen vacancies, interstitials) in the structure of pure and doped ZnO. Moreover, we fabricated gas sensors by spray-coating the AZO nanoparticles on alumina substrates equipped with interdigitated gold electrodes. The sensors demonstrated linear responses to gas concentration in the range of 5 to 50 ppm, with high sensitivity and good reproducibility, particularly for A1ZO (1% Al-doped ZnO), which exhibited the highest response (~12) at 300 °C under 10 ppm of acetone. Furthermore, A1ZO demonstrated excellent selectivity to acetone compared to other volatile organic compounds (VOC