Low-operating temperature and remarkably responsive methanol sensors using Pt-decorated hierarchical ZnO structure

Highly responsive methanol sensors working at low temperatures are developed using hierarchical ZnO nanorods decorated with Pt nanoparticles. The sensing materials are fabricated following a 3-step process: electrospinning of ZnO nanofibers, hydrothermal growth of hierarchical ZnO nanorods on the nanofibers and UV-assisted deposition of Pt nanoparticles. The morphology and characteristics of the materials are examined by field effect scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis absorption spectroscopy, and electrical measurements. The methanol sensing performance is investigated at different working temperatures in the range of 110-260 °C. It is observed that the surface modification of the ZnO hierarchical nanorods by Pt nanoparticles results in a remarkable enhancement of the sensing response toward methanol, which can reach approximately 19500 times higher than that of the unmodified ZnO nanorods-based sensor. In addition, this modification enables lowering the working temperature with an optimum range of 140-200 °C. Based on the achieved results, a methanol sensing mechanism of the Pt/ZnO structure is proposed.