The effects of annealing on gas sensing properties of ZnO nanorod sensors coated with Pd and Pt

Abstract

In this study, hydrogen (H2) gas sensing properties of palladium (Pd) & platinum (Pt) thin films coated and uncoated vertically alinged zinc oxide (ZnO) nanorods were investigated at different temperatures. On the other hand, the effects of annealing in dry air to gas sensing properties of the nanorods were investigated. Vertically aligned ZnO nanorods were fabricated by using hydrothermal method on glass substrate, and then Pd and Pt thin films was coated on to ZnO nanorods by using thermal evaporating system. The thickness of Pd or Pt thin film was approximately 15 nm. H2 sensing measurements were done in the temperature range of 25 - 200°C. It was found that the sensor response of Pd coated ZnO nanorods were much higher than uncoated ZnO nanorods because of catalytic effect Pd thin film. Moreover, unannealed samples showed better sensor response than annealed samples due to the surface charge number. The sensor response of all samples increased with enhancing temperature.