Synthesis, structure, and UV-enhanced gas sensing properties of Au-functionalized ZnS nanowires

Au-functionalized ZnS nanowires were prepared for use as gas sensors. Scanning electron microscopy revealed the diameters and lengths of the nanowires ranging from 20 to 100 nm and from a few tens to a few hundreds of micrometers, respectively. X-ray diffraction and transmission electron microscopy revealed that ZnS nanowires and Au nanoparticles were monocrystalline and polycrystalline, respectively. The responses of multiple networked ZnS nanowire sensors to 1-5 ppm NO2 were increased 1.6- to 1.9-fold and 2.8- to 5.4-fold by Au functionalization and a combination of Au functionalization and UV irradiation, respectively. Au-functionalized ZnS nanowire sensors showed responses of 168-313% to 1-5 ppm NO2 at 300 degrees C in the dark. These values are comparable or superior to most semiconductor oxide one-dimensional nanostructures-based sensors reported in the literature. Furthermore, Au-functionalized ZnS nanowire sensors showed far higher responses (291-884%) to 1-5 ppm NO2 at 300 degrees C under UV illumination. The NO2 gas sensing mechanism of the Au-functionalized ZnS nanowire sensors under UV illumination is discussed. (C) 2013 Elsevier B. V. All rights reserved.