Zinc oxide (ZnO) nanoparticles modified with uniformly dispersed silver (Ag) nanoparticles (Ag-ZnO) were prepared in one step by calcining precursor electrospun nanofibers. The molar ratios of Ag to Zn in the precursor solutions were 0, 1, 3, and 5%. The microstructure of the Ag-ZnO sensor was characterized by scanning electron microscopy and transmission electron microscopy. The existence of metallic Ag was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy, and the gas sensing properties of Ag-ZnO were investigated. The results showed that the ZnO nanoparticles after Ag nanoparticles modification exhibited excellent gas sensing performance to ethanol and hydrogen sulfide (H₂S). The optimal working temperature of the Ag-ZnO sensor significantly decreased for ethanol compared with pure ZnO. The 3% Ag-ZnO sensor exhibited the fastest response to ethanol with the response/recovery times of only 5 and 9 s, respectively. However, all the Ag-ZnO-based gas sensors showed a high response value to H₂S, especially the 3% Ag-ZnO gas sensor exhibited a maximum response value of 298 at 10 ppm H₂S. These results could be attributed to the spillover effect and electron sensitization effect of Ag nanoparticles, which led to more absorbed oxygen species and active sites, and thereby can further enhance the gas sensing performances of ZnO-based gas sensors.

Hierarchical SnO2 blooming nanoflowers were successfully fabricated via a simple yet facile hydrothermal method with the help of different surfactants. Here we focus on exploring the promotion effects of surfactants on the self-assembly of 2D SnO2 nanosheets into 3D SnO2 flower-like structures as well as their gas-sensing performances. The polyporous flower-like SnO2 sensor exhibits excellent gas-sensing performances to ethanol and H2S gas due to high porosity when polyvinyl pyrrolidone is added into the precursor solution as a surfactant. The response/recovery times were about 5 s/8 s for 100 ppm ethanol and 4 s/20 s for 100 ppm H2S, respectively. Especially, the maximum response value of H2S is estimated to be 368 at 180 °C, which is one or two orders of magnitude higher than that of other test gases in this study. That indicates that the sensor fabricated with the help of polyvinyl pyrrolidone has good selectivity to H2S.

Circularly polarized luminescence molecules with both thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) have been reported recently and are thought as potential candidates for circular polarized organic light-emitting diodes. Since the study of these kinds of systems is quite limited, it is of great importance to reveal the relationship between the geometry and the light-emitting mechanism. In this paper, the TADF and AIE mechanisms were studied based on the study of a series of binaphthalene-containing luminogenic enantiomers in both toluene and solid phases. It was found that there was no influence on the light-emitting properties of enantiomers except for the electronic circular dichroism (ECD). The radiative rates for both molecules were enhanced in the solid phase, while the non-radiative rates were significantly suppressed. Both factors can induce the AIE phenomenon. Based on the calculation of the decay rates and adiabatic excitation energy of the excited states, we found that the TADF mechanisms of the two molecules were different. One is realized by the up-conversion process between S₁ and T₁, while a two-step process is involved for the other. Our theoretical research successfully elucidates the experimental measurement and illustrates the AIE and TADF mechanism, which could provide valuable insights for the design of highly efficient CPL emitters.