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Metal–organic framework (MOF)-derived pure ZnO and Cu-doped ZnO nanocages were fabricated by calcining a zeolitic imidazole framework (ZIF-8) and Cu-doped ZIF-8. The morphology and crystal structure of the samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). It was found that Cu doping did not change the crystal structures and morphologies of MOF-derived ZnO nanocages. The H2S-sensing properties of the sensors based on ZnO and Cu-doped ZnO nanocages were investigated. The results indicated that the H2S-sensing properties of MOF-derived ZnO nanocages were effectively improved by Cu doping, and the optimal doping content was 3 at%. Moreover, 3 at% Cu-doped ZnO nanocages showed the highest response of 4733 for 5 ppm H2S at 200 °C, and the detection limit could be as low as 20 ppb. The gas-sensing mechanism was also discussed. [ABSTRACT FROM AUTHOR]

High‐sensitive detection of NO is very important to protect environment and human health. In this study, the composites of ZnO nanorods and CsPbBr3/Cs4PbBr6 particles are synthesized successfully and used as sensing materials for detection of NO, in which the as‐prepared samples exhibit ultra‐high response and excellent selectivity to NO at 50 °C. Toward 100 ppm NO, the response is up to about 2296. The samples can high‐sensitively detect 1 ppm NO with response of about 6, demonstrating a low detection limit. The high response of CsPbBr3/Cs4PbBr6/ZnO could be attributed to the multiple heterojunctions formed among three materials. The results demonstrated that the composites of CsPbBr3/Cs4PbBr6 and ZnO should be a promising material for preparing the high‐sensitive NO sensors at low temperature. [ABSTRACT FROM AUTHOR]

SnO2/ZnO@ZIF‐8 core‐shell nanofibers were synthesized by electrospinning and hydrothermal etching ZnO component of SnO2/ZnO nanofibers. It is found that the ZIF‐8 coated SnO2/ZnO nanostructures are obtained, and the ZIF‐8 coating can obviously increase the specific surface area of nanofibers. H2S sensing properties of the sensors based on composite nanofibers were investigated. The results show that SnO2/ZnO@ZIF‐8 core‐shell nanostructures can not only improve the response to H2S, but also effectively reduce the interference of ambient humidity on semiconductor gas sensors. The response of the optimal sample to 5 ppm H2S can reach 202.3, which is about 19 times higher than that of pure SnO2 nanofibers. Compared with the response at the ambient humidity of 55 %RH, the response at the ambient humidity of 90 %RH can still maintain 84.7 %. Good selectivity and stability are also observed in our investigations. [ABSTRACT FROM AUTHOR]

ZnO spheres composed of porous flakes were prepared by template-free, economical hydrothermal method combined with heat treatment. The high-density pores with the size in tens of nanometers were found distributed through each piece of the flake. The sensor based on porous ZnO spheres showed improved ethanol response compared to that based on commercial ZnO powders. ZnO spheres sensor showed obvious response to 2 ppm ethanol at the operation temperature of 280 °C, with the corresponding response value of 2.8 and the response and recovery times of 10 and 15 s, respectively. The response of the sensor increased linearly with the concentration of ethanol in the range of 2-500 ppm. The good sensing performance of the ZnO sphere sensor to ethanol gas indicated that the ZnO sphere could be a promising candidate as the building block for highly sensitive and reliable gas sensor. [ABSTRACT FROM AUTHOR]

Abstract: Pure and Ni-doped ZnO nanofibers were synthesized using the electrospinning method. The morphology, crystal structure and optical properties of the nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy, respectively. It is found that Ni doping does not change the morphology and crystal structures of the nanofibers, and the ultraviolet emissions of ZnO nanofibers present red shift with increasing Ni doping concentration. C2H2 sensing properties of the sensors based on the nanofibers were investigated. The results show that the C2H2 sensing properties of ZnO nanofibers are effectively improved by Ni doping, and 5at% Ni-doped ZnO nanofibers exhibit a maximum sensitivity to C2H2 gas. [Copyright &y& Elsevier]

Abstract: Undoped and Al-doped ZnO nanofibers were synthesized via a simple electrospinning method, and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman scattering and photoluminescence (PL) spectroscopy. The ethanol sensing properties of the sensor based on the nanofibers were also investigated. The results show that the sensor fabricated from Al-doped ZnO nanofibers exhibits better gas sensing performance than that fabricated from the undoped ZnO nanofibers, and the gas sensing mechanism is discussed. [Copyright &y& Elsevier]

Abstract: Pure and Cu-doped ZnO nanofibers were synthesized via electrospinning technology. The morphology and structure of the as-synthesized nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The effects of Cu doping on H2S sensing properties at low concentration (1–10ppm) were investigated at 230°C. The results show that the H2S sensing properties of ZnO nanofibers are effectively improved by Cu doping: 6at% Cu-doped ZnO nanofibers show a maximum sensitivity to H2S gas, and the response to 10ppm H2S is one order of magnitude higher than the one of pure ZnO nanofibers. [Copyright &y& Elsevier]

Abstract: Mg-doped ZnO nanofibers with different doping concentrations have been successfully synthesized by electrospinning method. The nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The results show that Mg doping has little influence on the diameter and surface morphology of ZnO nanofibers, and the nanofibers are crystalline and exhibit the hexagonal structure. The photoluminescence spectroscopy studies indicate that the ultraviolet emissions present blue shift with increasing Mg doping concentration. [Copyright &y& Elsevier]

Abstract: Well-aligned Cd–Al codoped ZnO nanorod arrays have been synthesized on Ni catalyst-coated p+-Si (111) substrates by a chemical vapor deposition technique. It is demonstrated that the obtained codoped ZnO nanorod arrays are single crystallinity with the wurtzite hexagonal phase and preferably grown along the [0001] direction. The optical properties of the nanostructures are characterized by the Raman and photoluminescence techniques. The rectifying characteristics of the p–n heterojunction composed of codoped ZnO nanorod arrays and a p+ silicon chip are observed. The possible growth process based on VLS mechanism is proposed for the formation of codoped ZnO nanorod arrays. [Copyright &y& Elsevier]