The Al³⁺ doped modified ZnO sensor material: Fabrication, characterization and gas sensing characteristics of some environmental pollutant and greenhouse gases

Abstract

The current study examines the gas sensing properties of the fabricated material Al3+ modified ZnO. The material was fabricated by using co-precipitation technique. Here, sodium hydroxide was used as precipitating material to precipitate zinc as zinc hydroxide to convert it finally into ZnO. The insitu doping method was adapted to doped aluminum through ZnO lattice. The material was characterized by means of several characterization techniques. The X-ray diffraction (XRD) instrument utilized for structural investigation of the prepared material. The mean particle size estimated 28 nm using the Debye-Scherer equation. Scanning electron microscopy (SEM) was utilized for surface and topographic properties of the prepared material, while energy dispersive x-ray spectroscopy (EDX) was utilized to get atomic weight percentage of elements. The ultra violet diffuse reflectance spectroscopy (UV-DRS) was used to find the energy band gap of modified ZnO. The hexagonal crystal lattice of the materials was confirmed from transmission electron microscopy (TEM) analysis. Thick films of Al3+ doped ZnO made using a screen printing technology. The developed thick film sensor of Al3+ doped ZnO was utilized to sense certain harmful gases such as toluene vapors (TV), LPG, petrol vapors, CO2 and CO. The material showed considerable response for CO and LPG at 500 ppm gas concentration with 85.20% and 76.23% gas response at 90°C and 120°C respectively. The other gas sensing characteristics of the materials was also examined for the fabricated Al3+ doped ZnO sensor such as response and recovery, reusability, ppm variation and gas response. From overall study it was observed that fabricated sensor Al3+ doped ZnO is reliable, and very rapid to detect the carbon monoxide vapors and liquefied petroleum gas vapors (LPG) at moderately high temperature and low gas concentration. The built sensor’s gas sensing mechanism was assessed to detect CO and LPG.

Al3+-modified ZnO thin film sensor fabricated by the sputtering method: Characterization and a carbon monoxide gas detection study

“…However, the size of the crystal decreases with an increase in the amount of Al 3+ . 37,38 Surface morphology of the thin films AFM was used to examine the pure and doped films prepared by the atomization method. Figure 2 shows the pure and Al-doped films as three-and two-dimensional (AFM) images.…”

“…The detect ions of harmful concentrations of carbon monoxide vapors using thin manufactured from pure and Al:ZnO films were based on the thickness of these films, after studying the effect of high temperatures on the electrical properties of these films. The gas response is calculated according to the following formula 38 Gas response R Ra Rg Ra 1 % /…”