Structure-dependent gas detection ability of clustered ZnS crystallites with heterostructure and tube-like architecture

Abstract ZnS crystallites with a core–shell heterostructure (ZnO–ZnS core–shell rods) and tube-like architecture were synthesized through a facile chemical solution route. Many tiny ZnS particles were clustered and compacted to form the shell layer of the ZnO–ZnS core–shell rods and the wall of the ZnS tubes during sulfidation of vertically aligned ZnO rods. X-ray diffraction and transmittance electron microscopy images revealed that the ZnS shell layer of the ZnO–ZnS core–shell rods and the wall of the tubes were polycrystalline, and that many domains or grain boundaries were present in the ZnS layers. The sensitivities of ZnO–ZnS core–shell rods and ZnS tubes to reducing and oxidizing gases differed. The ZnO–ZnS core–shell rods were more sensitive to reducing gases, whereas the ZnS tubes were more sensitive to oxidizing gases. The different gas sensing properties of the ZnS-based heterostructures and tubes are further discussed in relation to their microstructures. The heterojunction at the ZnO/ZnS interfacial region resulted in the differing gas sensing properties of the ZnS-based heterostructures and tubes in this study.