Enhanced sensing of acetone by Al–ZnO synthesized using microwave-assisted combustion

Abstract

Detection of high-concentration acetone at low operating temperatures is crucial for safety in industry. In this study, we have reported a 242% acetone (500 ppm) sensing response by a 5% Al–ZnO sample at 60 °C and documented the synthesis of the parent ZnO and its composites with ZnAl₂O₄ containing different Al contents, namely 2%, 5%, and 10% Al–ZnO, by a microwave-assisted combustion method (fast exothermic redox reaction between zinc nitrate and aluminium nitrates). XRD analysis with Rietveld refinement confirmed the coexistence of ZnO and ZnAl₂O₄ phases, whereas UV-vis and SEM analysis revealed optical and morphological changes. Gas sensing studies showed remarkable enhancement in acetone sensing by 5% Al–ZnO in comparison to methanol, ethanol, isopropanol and benzene. The 5% Al–ZnO sample exhibited the highest sensing response of ∼242% at 500 ppm with response and recovery times of ∼272 and ∼48 s. The superior performance of 5% Al–ZnO can be attributed to the synergistic effect of the ZnAl₂O₄ phase, which allows efficient charge transfer and enhances the adsorption–desorption kinetics even at high concentrations. Overall, the microwave-assisted combustion method appears to be an efficient and effective method for producing Al–ZnO with excellent acetone sensitivity and selectivity over a wide range of concentrations at low temperatures.