High gas sensing performance of one-step-synthesized Pd-ZnO nanoflowers due to surface reactions and modifications.

Pd-ZnO nanoflowers with high uniformity were prepared via a novel one-step hydrothermal route. High sensitivity, fast response, high selectivity and low work temperature are obtained from Pd-ZnO nanoflower sensors. The sensitivity upon exposure to 300 ppm ethanol is up to 168 at 300  °C and maintains 2.6 at 120  °C. Such behaviors can be attributed to Schottky contact at the Pd/ZnO interface and catalytic activity of Pd nanoparticles. The present results open a way for uniform surface modification of one-dimensional nanostructures with Pd nanoparticles and further enhancing their gas sensing performance.