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The volatile organic compounds (VOCs) sensing layers were studied using ZnO nanomaterials with different morphologies including hierarchical nanostructure (ZnO-H), nanorods (ZnO-NRs), commercial nanoparticles (ZnO-CNPs) and wet chemical synthesized nanoparticles (ZnO-HNPs). ZnO hierarchical structure was fabricated by an electrospinning technique followed by hydrothermal process. ZnO vertical nanorods structure was fabricated by hydrothermal method, while ZnO nanoparticles based sensors were prepared from commercial powder and wet chemical method. The morphology and properties of the fabricated samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). VOCs sensing responses toward acetone, ethanol and methanol with respect to altered ZnO nanostructureswas systematically compared at different working temperatures. The enhanced response at low working temperatures induced by theopen space hierarchical structure was observed. The VOCs sensing mechanisms of the ZnO nanostructures based sensing layer were also explained and discussed in detail.

The improvement in the response property of acetone sensors has been investigated using sensing layers of CuO/ZnO hierarchical nanostructure under UV irradiation. ZnO hierarchical structure was fabricated by hydrothermal sprouting of ZnO nanorods around ZnO nanofibers, which is fabricated by electrospinning method followed by thermal oxidation. CuO particles were decorated on the ZnO surface by optical deposition method. The acetone sensing properties of pure ZnO and CuO/ZnO sensors have been studied. The results showed that CuO/ZnO sensors had a higher response to acetone vapor than pure ZnO sensors at most of the operating temperatures. The highest response of 3929% towards 1,863% acetone vapor at operating temperature of 240°C was observed by CuO(2)/ZnO structure under UV irradiation. The mechanism of acetone sensing of CuO/ZnO materials are also discussed in detail. The morphology and structural properties of the materials were investigated based on SEM, TEM, EDS and XRD.

Cu doped ZnS microstructures were prepared by the thermal evaporation method using ZnS powder and CuCl2.2H2O powder as precusor materials. The microstructures was characterized by using X-ray diffraction (XRD) analysis. The XRD studies indicated that there are two phases (ZnS and ZnO) at the undoped sample, but most of the samples are only having wurtzite (hexagonal) phase of ZnS after doping. The photoluminescence emission and photoluminescence excitation of ZnS and Cu2+ doped ZnS microstructures have been studied. The photoluminescence excitation spectra of ZnS microstructures is present around 374 nm. After doping of Cu2+ ion the absorption wavelength shifted towards the lower wavelength, this blue shift in the absorption edge is a measure of increased band gap. The emission spectrum of pure ZnS has a green emission band centred at around 520 nm. After doping with Cu2+ ion the luminescence centers were transferred to 516 nm and a strong blue peak at 440 nm appears. The reasons of these will be discussed in this paper.

We present an investigation of the morphology, structure, composition and optical properties of ZnS:Mn2+ microbelts grown by the thermal evaporation method using ZnS powder and MnCl2.4H2O powder as precursor materials. The SEM images of the products show that ZnS:Mn2+ microbelts are bigger and shorter than ZnS microbelts. EDS reveals that the composition of the microbelts include Zn, S, O, Mn and Cl elements. The atom rate of oxygen composition of the doped microbelts seem to be slightly lower than undoped ones. XRD pattern of the prepared microbelts shows that ZnO coexists with ZnS on the undoped microbelts. However, at the Mn-doped microbelts, the component phase of ZnO is disappeared. Photoluminescence spectra of undoped ZnS microbelts reveal a strong broad emission band at visible wavelength region and a weak ultraviolet band. Interestingly, when Mn2+ is doped into the microbelts, the visible emission band is separated into blue, green, and yellow bands peaking at around 442, 520 nm, and 572 nm, respectively. The effects of Mn2+ ions on the emission bands is discussed in detail.

In this paper, we present about influent of temperature at the possitions where we puted the silica substrates on morphology, phase and photoluminescence of ZnS microstructures by thermal evaporation of ZnS powder in Ar gas ambient at atmospheric pressure. From X-ray diffraction pattern (XRD), the prepared microstructures have wurtzite (hexagonal) structures for ZnS phase and appear ZnO phase at lower temperature areas. The morphology of the microstructures change depending on substrate temperatures. The photoluminescence spectrum (PL) at room temperature shows that the shift from ultraviolet (UV) emission at high substrate temperature to strong blue emission at lower substrate temperature. The reasons of these peaks will be discussed in detail.

In this work, we report on the controlled synthesis of ZnS microstructures with high purity on Au-coated silicon substrates by thermal evaporation of ZnS powder in Ar gas ambient at atmospheric pressure. The growth mechanism is confirmed as a typical vapor–liquid–solid process. The prepared ZnS microstructures have wurtzite (hexagonal) structures. The catalytically grown ZnS microstructures, including microwires and microbelts, are tens of micrometers in length. EDS shows that the oxygen composition in the microstructures is trivial. The photoluminescence spectrum reveals strong ultraviolet emission and no other emission at room temperature also demonstrates that the ZnS microstructures are of high crystalline perfection. Optical transition from free exciton A, free exciton B are observed and analyzed through power-dependent at 10 K and temperature-dependent photoluminescence spectroscopy measurements performed from 10 to 300 K. Our results indicate that ZnS microstructures grown by thermal evaporation, suggesting a great promise for high-efficiency light-emitting devices and lasers in the UV region.