Enhanced response of porous ZnO nanobeads towards LPG: Effect of Pd sensitization

The nanoporous ZnO films consisting of nanostructural beads were prepared by pyrolytic decomposition of an aqueous zinc nitrate solution and their liquid petroleum gas (LPG) sensing properties were studied. The response of the ZnO nanobeads towards LPG was enhanced significantly by palladium (Pd) sensitization which was deposited onto the ZnO nanobeads by a sequential dipping and drying method. The LPG sensing properties of the ZnO nanobeads and Pd-sensitized ZnO were investigated at different operating temperatures and different gas concentrations ranging from 0.1 to 0.4 vol%. The unsensitized ZnO nanobeads exhibited the maximum response of 31% at 673 K upon exposure to 0.2 vol% LPG which was improved up to 63% at the optimum temperature of 548 K by Pd sensitization. Additionally, the Pd-sensitized ZnO was able to respond very quickly to the exposure of LPG.