Templating synthesis of ZnO hollow nanospheres loaded with Au nanoparticles and their enhanced gas sensing properties

Au-loaded ZnO hollow nanospheres have been successfully synthesized by using carbon nanospheres as sacrificial templates. This simple strategy could be expected to be extended for the fabrication of similar metal-oxide loaded hollow nanospheres using different precursors. The structural and morphological characteristics of the resultant product were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The hollow nanospheres are porous, with the diameters ranging from 220 to 280 nm. To demonstrate the usage of such Au-loaded ZnO nanomaterial, a chemical gas sensor has been fabricated and investigated for NH3 detection. The Au-loaded ZnO sensor exhibits excellent sensing performances compared with hollow ZnO and compact ZnO sensors. The dynamic transients of the Au-loaded ZnO sensors demonstrated both their fast response (0.8-1.5 s) and recovery (3-4 s) towards NH3 gases. The combination of ZnO hollow structure and catalytic activity of Au loaded gives a very attractive sensing behavior for applications as real-time monitoring gas sensors with fast responding and recovering speed.