Porous ZnO nanosheets exhibit superior sensitivity in ethylene detection and present different intensity responses to bananas at different maturity stages.

In present work, the CdS nanoparticle decorated ZnO porous nanosheets (CdS NP/ZnO PNs) were successfully synthesized through a facile wet-chemistry method. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrum. The results proved the porous and monocrystalline structures of the ZnO nanosheets. A huge number of tiny CdS nanoparticles evenly cover the surface of the ZnO porous nanosheets, and the average size of the CdS nanoparticles is about 5 nm. The CdS NP/ZnO PNs exhibit excellent sensing activity and selectivity towards isopropanol. The linear response range is 1-100 ppm under the optimized operation temperature of 320 °C, and the detection limit is 1 ppm. The sensing performance of the CdS NP/ZnO PNs towards isopropanol is dramatically higher than that of other VOC gases, indicating the high selectivity to isopropanol. The CdS NP/ZnO PNs based sensor even can distinguish isopropanol from the complex mixed gases. Besides, the responses of the as-prepared sample to isopropanol seldom changed within 15 days. It is believed that the CdS NP/ZnO PNs have great application potential in isopropanol detection.

In this work, graphene-oxide-decorated porous ZnO nanosheets were prepared using a hydrothermal method. The graphene oxide/porous ZnO nanosheet (GO/ZnO nanosheet) composites were characterized with SEM, HRTEM, XRD, Raman spectroscopy, XPS and BET. The results indicate that the ZnO nanosheets have a porous, single-crystal structure. Thin GO nanosheets closely cover the surface of porous ZnO nanosheets. The sensing performance of GO/ZnO nanosheet composites is investigated. At the optimized temperature of 300 °C, the GO/ZnO nanosheet composites exhibit a superior sensing performance in n-propanol detection. In a wide range of 5–200 ppm, the composites exhibit a linear response to n-propanol. Moreover, the sensing performance of the GO/ZnO nanosheet composites to n-propanol is largely higher than that to other VOC gases, indicating a high selectivity in n-propanol detection. This can be ascribed to the higher electron-separation efficiency and larger depletion layer brought by the modification of the GO on ZnO nanosheets. It is considered that the GO/ZnO nanosheet composites have a great application potential in n-propanol detection.