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ZnO nanostructured materials have been widely utilized in several environmental depollution applications. In the current work, ZnO nanorods were grown using the electrodeposition method with different precursor concentrations. A variation in the dimensions of the nanorods grown with the different precursor concentrations was noticed, as expected. The ability of the fabricated nanorods to remove water pollutants under UV irradiation and their photocatalytic performance stability was also evaluated over a prolonged period of time. Interestingly, the samples grown in different conditions exhibited different capabilities to maintain their morphology and their photocatalytic performance after they were kept in contaminated water for a long time. Moreover, some samples also were found to remain photocatalytically active for approximately 47% longer than other samples. These findings indicate that the performance stability of ZnO nanorods for pollutants removal and their robustness can be greatly improved by controlling their growth parameters, which will favorably impact the use of ZnO nanorods for water-treatment applications and their economic aspects. [ABSTRACT FROM AUTHOR]

In the current study, a comparison between the different Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites with respect to their structural, morphological, optical and photocatalytic properties is presented. The nanostructure nature of the investigated composites was confirmed by the XRD and SEM analysis. The nanocrystalline ZnO, M3O4, CuO and Fe2O3 phases were observed with different crystalline structure, including hexagonal, tetragonal, monoclinic and rhombohedral, respectively. The morphology of ZnO based nanocomposites was found to be dependent on the type of the metal oxide added to ZnO nanostructure. In addition, the studied nanocomposites showed different optical properties. The highest and lowest band gap of 3.14 and 2.00 eV were obtained for ZnO nanoparticles and Fe2O3/ZnO nanocomposite. Concerning the photocatalytic properties, the ZnO nanoparticles, Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites showed an efficiency of 49.63, 29.8, 11.61 and 95.34%, respectively, for the photodegradation of methylene blue. The Fe2O3/ZnO nanocomposites exhibited the highest activity for water purification compared to the other nanocomposites. [ABSTRACT FROM AUTHOR]

The main goal of the present paper is to fabricate ZnO nanorods (NRs) as well as to investigate their structural, optical and photocatalysis properties. The proposed study could help in the development of these materials to be used in optoelectronic and water treatment applications. The ZnO NRs were synthesized on gold (Au)-coated glass substrates by electrochemical deposition technique. The SEM images demonstrated the uniform and dense development of ZnO NRs. The NRs' average diameter and length increased from 87 to 368 and from 357 to1600 nm, respectively, by increasing the growth time from 30 to 180 min. The ZnO NRs have hexagonal crystalline structure and grow in the direction of the (200) plane. The optical absorption analysis showed a decrement of the band gap of ZnO NRs from 3.17 to 2.69 eV by the variation of time from 60 to 180 min. The refractive index, dissipative factor and electron loss functions were affected also by the deposition time. The photocatalytic activity of ZnO NRs was improved by an increase in both irradiation and deposition time. [ABSTRACT FROM AUTHOR]

• GO/ZnO nanocomposites with different oxidation levels and different ZnO NPs contents were prepared. • The effect of GO oxidation level and ZnO NPs contents on the nanocomposite pollutants removal efficiency was investigated. • GO processing conditions and ZnO NPs content were found to play a major role in the nanocomposites performance. • The investigated factors can be utilized to maximize the pollutant removal ability of GO/ZnO nanocomposite. • A pollutant degradation efficiency as high as 98 % was achieved through a proper optimization of GO/ZnO nanocomposite. Nanocomposites are promising materials for many applications including environmental ones. Herein graphene oxide / zinc oxide nanocomposites were prepared using simple chemical methods and used to purify polluted water samples. Highly dispersed and uniformly decorated GO nano-sheets with ZnO nanoparticles were synthesized and were utilized for water treatment applications. Two factors were investigated: GO treatment time and ZnO NPs content in the nanocomposite and both were found to strongly affect the nanocomposite performance in degrading methylene blue. They were also found to govern the contribution of each nanocomposite constituent, GO and ZnO NPs, in pollutant removal process. Through a proper optimization of these factors, a pollutant degradation efficiency as high as 98 % was achieved. The findings show that the performance of graphene based nanocomposites for water treatment applications can be greatly enhanced by a proper control of their processing conditions and the content of each constituent of the nanocomposite. [ABSTRACT FROM AUTHOR]

The current work presents the optical, photoluminescence and ferromagnetic properties of Zn1−xNixO samples with (0.00 ≤ x ≤ 0.20). The samples are well crystallizing in hexagonal wurtzite structure without a significant change in their lattice constants, while the crystallite size, grain size and number of unit cells in ZnO particle are increased. The residual stress is negative (compressive) and almost increases as Ni increases up to 0.10, but it is changed from negative to positive (tensile) at Ni = 0.20. The absorption and reflectance of UV spectra are increased as Ni increases up to 0.20. An absorption band centered at a wavelength of 552 nm is also observed and is gradually shifted by Ni towards longer wavelengths. Interestingly, two direct electronic transitions are found for all samples and two induced bandgaps which are decreased by Ni. While the other optical constants such as linear χ1 and non-linear third-order susceptibilities χ3, dispersion parameters (Ed, Eo), refractive indexes (no, n2), lattice dielectric constant εL, N/m*, optical and electrical conductivities (σopt, σele) are increased by Ni, the dissipation factor (tanδ) is decreased. Although some of the continuous peaks of lower PL intensities are recorded at UV band edges and slightly shifted to longer wave lengths (red shift) as Ni increases, strong UV emission peaks at about 390, 420 and 440 nm are recorded. Finally, the signature of a clear weak ferromagnetism ordering at room temperature, with evaluated magnetic parameters such as magnetization Ms, magnetic moments μ and magneto-crystalline anisotropy factor γ, is recorded for Ni ≥ 0.05 doped samples. [ABSTRACT FROM AUTHOR]

Cd–ZnO–Na alloy nanostructured thin films were synthesized via sol–gel spin coating method on glass substrates and the effect of Na (1, 2 and 3 wt%) doping variation on linear, nonlinear optical, opto-dielectric, and emission properties of the films was investigated. The variations in physical properties with different Na doping concentrations were analyzed using X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), FT-Raman, UV–Vis, and photoluminescence spectroscopy. From XRD patterns, it was observed that the growth of the films occurs along (002) plane with hexagonal wurtzite structure. High percentage of transmittance (viz. 85 to 90%) was recorded for all as grown films. However, the estimated bandgap energy of the films was found to decrease from 3.37 to 3.30 eV with increasing Na doping concentration from 1 to 3 wt%. Emission spectra of the films show an intense and sharp peak near band emission (NBE) at 389 nm whereas a low intense peak was observed at 475 nm. The intensity of NBE peak specifies the significant enhancement in photoluminescence properties of the grown films with increasing Na doping concentrations. Nonlinear optical parameters of the Cd–ZnO–Na films such as χ3 and n2 showed substantial improvements, which were deduced and obtained in the range 1.11 × 10–14–1.91 × 10–12 esu and 5.20 × 10–13–3.19 × 10–11 esu, respectively. The achieved improvement in the grown ZnO films via co-doping with Cd and Na makes them highly suitable candidates for optoelectronics devices applications. [ABSTRACT FROM AUTHOR]

The fabrication of highly functionalmaterials for practical devicesrequires a deep understanding of the association between morphologicaland structural properties and applications. A controlled hydrothermalmethod to produce single crystal ZnO hexagonal nanodisks, nanorings,and nanoroses using a mixed solution of zinc sulfate (ZnSO4) and hexamethylenetetramine (HMTA) without the need of catalysts,substrates, or templates at low temperature (75 °C) is introduced.Metal–semiconductor–metal (MSM) ultraviolet (UV) detectorswere fabricated based on individual and multiple single-crystal zincoxide (ZnO) hexagonal nanodisks. High quality single crystal individualnanodisk devices were fabricated with inkjet-printed silver electrodes.The detectors fabricated show record photoresponsivity (3300 A/W)and external quantum efficiency (1.2 × 104), whichwe attribute to the absence of grain boundaries in the single crystalZnO nanodisk and the polarity of its exposed surface. [ABSTRACT FROM AUTHOR]

Cd and Na co-doped ZnO nanostructured thin films with different doping concentrations were prepared using a sol-gel spin coating technique on glass substrates. The effect of doping with Cd and 1, 2 and 3 wt % Na on the structural, morphological, optical and UV detection properties of the nanostructured ZnO thin films was investigated. The grown co-doped nanostructured thin films exhibit wurtzite structure with preferential growth along the (002) plane. The change in the doping concentration was found to have a considerable effect on the grain size of the prepared films as well as their morphology. A variation in the band gap of the co-doped nanostructured thin films was also observed with changing the doping concentration. The band gap was found to vary in the range from 3.27 to 3.24 eV with increasing Na concentrations. The UV detection performance of the co-doped ZnO nanostructured thin films based UV detector was also investigated and found to strongly depend on the dopants concentrations with an obvious correlation with the variation in the films band gap. The findings of the current study show that a good control of the optical properties and the UV detection performance of the ZnO nanostructured thin films can be achieved through co-doing with Cd and Na with increased potential for their uses in high performance opto-electronic devices. • High quality ZnO nanostructured thin films co-doped with Cd and Na were prepared using sol-gel method. • The effect of co-doping with Cd and Na on the optical properties and the UV-detection performance of the films is reported. • Cd and Na co-doping significantly improves the UV detection performance of ZnO films based devices. • Co-doping with Cd & Na could be an effective route to improve the performance of ZnO based opto-electronic applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • UV detection of nanostructure thin films was analyzed in correlation of grain size of films. • UV detection of nanostructure thin films was analyzed in correlation of grain size of films. • Optoelectronic performance of films considerably dependence on rpm. Here we report on the development of ZnO nanostructured thin films-based UV detectors, fabricated via cost effective sol–gel spin coating method. The prepared films possess hexagonal wurtzite structure with strong texturing along the [0 0 2] directions. Morphological studies of the films confirm the formation of nano-sized granular structures. It was found that the UV detection performance of these nanostructured films is decreased spectacularly, about thirty-fold, by reducing the grains size from 23 nm (at 1500 rpm) to about 11 nm (at 3000 rpm). The grain sizes and optical band gaps of the films were found to considerably vary with the rpm. In addition to the high UV detection performance, the prepared films show about 85–90% optical transmittance in the visible region of the solar spectrum. Our study provides a cost-effective approach for performance improvements of ZnO nanostructures based optoelectronic devices. [ABSTRACT FROM AUTHOR]

We report the investigation of structure, morphology, photocatalytic degradation of methyl blue using ZnO nanorods (NRs). The ZnO NRs samples were fabricated using electrochemical deposition from aqueous solution of zinc nitrate and hexamethylenetetramine on ITO substrates. The effect of the growth time on the structure, morphology and photocatalytic properties of ZnO NRs was investigated in details.XRD analysis showed that the fabricated NRs have hexagonal wurtzite structure and growth direction along the (002) plane. The morphology of the prepared samples investigated by SEM showed that growth rate of the NRs depends on the time of the growth. The surface area and cross-sectional area of the fabricated ZnO NRs increased with increasing the growth time and led to improvements in the NRs aspect ratios. It was also found that the photocatalytic activity of the grown nanorods enhances by increasing the deposition time. The present results are discussed in terms of the observed structural morphology of the investigated ZnO NRs and correlated with the photocatalytic performance of the grown NRs. [ABSTRACT FROM AUTHOR]

Zn 1-x Bi x O samples' structural, optical, and photocatalytic properties, with (0.00 ≤ x ≤ 0.20), have been investigated. By increasing the Bi content to 0.20, the a-parameter, unit cell volume, crystallite size and porosity increased, while c-parameter decreased.. Interestingly, adding Bi to ZnO increases the Young and bulk modulus, and all samples are brittle in nature. The optical analysis revealed that all Zn 1-x Bi x O samples have two direct band gaps (E g1 /E g2) in which their values are reduced by increasing the Bi content to 0.10, and then an increase up to 0.20 of Bi. The reflective index of ZnO is increased by the introduction of Bi3+ ions into the host material. The activity of the photocatalytic is reduced by doping of 0.025 Bi, but it is enhanced by changing the Bi content to 0.20. These findings reveal that Zn 1-x Bi x O nanoparticles are more suitable for optoelectronic devices, and water purification. • The unit cell volume, crystallite size and porosity were increased by doping. • Adding Bi to ZnO increased the elastic modulus, and all samples are brittle. • Two direct band gaps were observed for Zn1-xBixO nanoparticles. • The photocatalytic activity is enhanced by changing the Bi content to 0.20 • Zn1-xBixO nanoparticles are promising materials for optoelectronic and water purification technology. [ABSTRACT FROM AUTHOR]