Effect of Al and Mg Co-doping on the Microstructural and Gas-Sensing Characteristics of ZnO Nanoparticles

Al and Mg co-doped ZnO nanoparticles were synthesized via the sol-gel technique to detect carbon oxides. The impact of Al and Mg on the structural, morphological and optical properties was discussed. XRD patterns revealed that Al and Mg ions successfully incorporate within the hexagonal crystalline structure of ZnO. The crystallites sizes of the samples heated at 400 °C ranges between 23 and 27 nm. TEM characterizations showed prismatic-like shape crystallites. Optical characterizations were carried out by UV-VIS-NIR spectroscopy and photoluminescence, showing high absorbance in the UV region and a slight decrease in energy band-gap compared to undoped ZnO. The PL spectra of all samples illustrated two major emissions including a broad visible band and a narrow ultraviolet (UV) band. Finally, it was confirmed that Al-Mg co-doping ZnO films promote carbon oxides sensing properties in terms of higher response, low detection limit and lower response/recovery time in comparison with undoped ZnO film.