Synthesis and Characterization of Mg-doped ZnO Nanoparticles for Gas-sensing Applications.

Undoped ZnO and Mg-doped ZnO (ZnO:Mg) nanoparticles (NPs), with Mg concentration ranging from x = 1 to 5 at%, were synthesized by the sol–gel method. The magnesium content effects on the different ZnO:Mg NPs properties have been investigated by a variety of techniques. X-ray results showed that the prepared samples were crystalline with a hexagonal wurtzite phase. The structural study revealed that samples are assembled in nanostructures with average crystallite sizes ranging from 37 to 41 nm. The elemental analysis confirms the incorporation of the Mg ions into the ZnO matrix. The TEM images show the hexagonal shape and the nanometric size of undoped ZnO and ZnO:Mg NPs. The estimated bandgap energies of the ZnO:Mg samples were 3.20 eV, 2.86 eV, 2.77 eV, and 2.99 eV for x = 0, 1, 3, and 5 at%, respectively. The ethanol-sensing properties of ZnO:Mg(3%) NPs, prepared in the form of film, were investigated in the temperature range of 300–400 °C at different ethanol concentrations. The linear responses from ZnO and ZnO:Mg NPs-based sensors were detected at the working temperature of 400°C in the 30–50 ppm level range. The obtained results outline an enhancement in sensing performances for a ZnO:Mg(3%)-based sensor towards ethanol gas compared to those of a pure ZnO-based sensor. The sensors exhibited short response and rapid recovery times, 4 and 23 s, respectively, to ethanol gas. The high, reversible, and fast response of the ZnO:Mg(3%)-based sensor indicates its potential application as a gas sensor to detect ethanol. [ABSTRACT FROM AUTHOR]