Toluene and ethanol sensing performances of pristine and PdO-decorated flower-like ZnO structures

The flower-like pristine (ZnO) and PdO-decorated ZnO (PdO-ZnO) materials with hierarchical structure were synthesized by a surfactant-free hydrothermal route and subsequent heat treatment. This method requires high concentrations of a zinc precursor (0.1 M) and introduction of an amount of PdO nanoparticles into the reaction system. The flower-like ZnO nanostructures comprises many aggregative rods with the diameter of about 200 nm. Having fabricated gas sensors based on the pristine and PdO-decorated flower-like ZnO, we find that the PdO-ZnO sensor exhibits a response of 100 ppm C7H8 and C2H5OH, which is about 4-5 times higher than that of pristine ZnO at the optimal operating temperature of 240 and 320 °C. The enhanced sensing performance demonstrates that the distinct increases in response are attributed to the sensitisation effect of PdO. The effects of PdO decorating on the sensing properties of flower-like ZnO structures have been investigated.