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.