Zinc oxide core–shell hollow microspheres with multi-shelled architecture for gas sensor applications

A new type of spherically multilayered core–shell structure was prepared via a simple hard template strategy in the case of ZnO. The structure and morphology 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 ZnO microspheres with hollow interior and porous shells are multilayered structures with diameters ranging from 0.4 to 3.5 μm. Further investigation of the formation mechanism reveals that the preheating program is vital to the formation of the multishelled structures. To demonstrate the usage of such a multilayered nanomaterial, a chemical gas sensor has been fabricated and investigated for toluene detection. The sensor exhibits excellent sensing performances in terms of high response, low detection limit, rapid response-recovery, and superior selectivity.