Enhancement of gas-sensing abilities in p-type ZnWO4 by local modification of Pt nanoparticles.

Semiconducting ZnWO4 nanorods and nanoparticles are synthesized by adjusting the composition of the reaction solvent. The effect of Pt nanoparticles on the sensing property of ZnWO4 nanostructures were evaluated and investigated systemically in the first time. Pure ZnWO4 nanostructures exhibited the highest sensitivity towards ethanol against Volatile Organic Compounds (methanol, acetone). Their lower limit of detection can reach 100 ppm for ethanol at temperature of about 23 °C. Pt nanoparticles play a positive effect in improving the sensitivity of ZnWO4 towards H2. After loading of Pt nanoparticles, the response of ZnWO4 nanorods towards 1.5% H2 increased from 1.4 to 12.5 at room temperature. In addition, the structure exhibits more significant promoting effect than nanoparticle structure because of their different microstructure and exposed crystallographic planes. Furthermore, Pt nanoparticles could eliminate the effect of ambient humidity to avoid the baseline shift. The gas sensing mechanism of PtZnWO4 nanocomposites is discussed detailedly at the same time. The generation of Schottky barrier at the interface between metal and semiconductor, as well as the formation of PtO on the surface of Pt nanoparticles contribute to the enhanced sensing response.