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Molybdenum ions with high valence states (Mo6+) can contribute to electrical conductivity and optical transmittance. For this reason, zinc oxide (ZnO) nanorods doped with molybdenum metal were fabricated on a glass substrate by ultrasonic spray pyrolysis method. The doping concentrations were between 0–10 mol%. The crystallographic properties of the resulting ZnO samples were examined by the X‐ray diffraction (XRD) technique. According to the XRD analysis, it was found that the lattice structure of the samples belonged to the hexagonal (wurtzite) unit cell. The XRD results indicated that the crystals grow in the c‐axis (002) direction. The morphological features of the obtained thin films were studied by field emission scanning electron microscopy. The energy‐dispersive X‐ray spectroscopy results displayed that the Mo ions were in the ZnO lattice. Four point probe method was used to determine the electrical conductivity properties of the samples. The 10% mol doped sample has the highest conductivity with values of between 1.58 × 10−9 and 1.58 × 10−6 (ohm‐cm)−1. The optical transmittances of the samples were measured at wavelengths between 300 and 1000 nm. It was observed that the produced films had high optical transparency which was approximately 85%. [ABSTRACT FROM AUTHOR]

Dried plum-like ZnO assemblies consisting ZnO nanoparticles were synthesized by an ultrasonic spray pyrolysis method (USP). ZnO assemblies were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS) and field-emission transmission electron microscopy (TEM). The results show the size of ZnO assemblies is in the range of 300–870 nm, and that of ZnO nanoparticles is from 33 nm to 39 nm. The microstructure and size of ZnO assemblies were successfully controlled by the concentration of the precursor solution. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Core-shell Ag/ZnO nanocomposites were synthesized by USP method. • By XRD, Wurtzite (ZnO) and face-centered-cubic (Ag) structures have been identified. • 2-steps route gives consecutive precursor precipitation, improving silver deposition. • Environmental applications of Ag/ZnO synthesized samples are promising. • The optimum Ag+/Zn2+ = 0.2 molar ratio aims the highest photocatalytic activity (93%). Abstract Spherical core-shell Ag/ZnO nanocomposites were synthesised by ultrasonic spray pyrolysis (USP) method from zinc nitrate hexahydrate, Zn(NO 3) 2 ·6H 2 O (ZN) and silver nitrate, AgNO 3 (SN) precursors. Varying solution concentrations and equipment installations (either single − or two-step USP) allowing simultaneous and consecutive precipitation of Ag and ZnO were examined regarding their effect on final particle microstructure and photocatalytic properties. Morphological analyses revealed pure Ag/ZnO core-shell structure where ZnO secondary submicron sized particles formed by primary crystals with the size of 5–20 nm. Depending on the solution concentrations and USP installations, various distributions of Ag in the final microstructure was revealed. Photocatalytic analyses (all samples reached >45% MB degradation) confirm the all Ag/ZnO USP systems viability for environmental applications. The best result (93% of methylene blue (MB) elimination) is obtained for the sample with the maximum available surface, which strongly depends on particle morphology, size, and dispersion. Moreover, all samples synthesised by single step co-precipitation revealed higher dye elimination concerning ones with two steps precipitation due to the favoured distribution of silver nanoparticles in their microstructure and higher specific surface area. Moreover, samples with a uniform and homogeneous Ag distribution exhibited silver-induced enhancement of photocatalytic performance. [ABSTRACT FROM AUTHOR]

ZnO nanoparticles were synthesized in a horizontal three zones furnace at 500 °C using different zinc nitrate hexahydrate concentrations (0.01 M, 0.1 M, and 1.0 M) as a reactive precursor solution by air assisted Ultrasonic Spray Pyrolysis (USP) method. The physico-chemical, structural and functional properties of synthesized ZnO nanoparticles have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), Brunauer, Emmett and Teller (BET) method, UV–vis spectroscopy and photoluminescence (PL) measurements. Also, the photocatalytic activities of ZnO synthesized from different precursor concentrations were evaluated by removal rate of methyleneblue (MB) under UV irradiation (365 nm) at room temperature. SEM revealed two types of ZnO nanoparticles: a quasi-spherical, desert-rose like shape of the secondary particles, which does not change significantly with the increasing of precursor solution concentration as well as some content of the broken spheres. Increasing the precursor solution concentration leads to the increase in the average size of ZnO secondary particles from 248 ± 73 to 920 ± 190 nm, XRD reveals the similar tendency for the crystallite size which changes from 23 ± 4 to 55 ± 12 nm in the analyzed region. HRTEM implies the secondary particles are with hierarchical structure composed of primary nanosized subunits. The PL spectra imply a typical broad peak of wavelength centered in the visible region exhibiting the corresponding red-shift with the increase of solution concentration: 560, 583 and 586 nm for the 0.01, 0.1 and 1.0 M solution, respectively. The reported results showed the photocatalytic efficiency of ZnO nanoparticles was enhanced by increased precursor concentration. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ag/ZnO nanocomposite catalyst with a single step route is synthesized. [•] Methylene Blue decolorization, degradation and first order kinetics is studied. [•] The highest decolorization and degradation rates are 40% and 27% respectively. [•] The highest degradation rate coefficient is 9×10−3 min−1. [•] Crystallite sizes and atomic fraction difference are important parameters. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ag-supported ZnO particles were generated using the spray pyrolysis method. • Ag/ZnO particles with high efficiency showed twice the photolysis activity of P25. • The generated particles were recovered by gravity sedimentation and reused. • Change of Ag nanoparticles was not observed after the photolysis experiment. Environmental issues caused by the rapid industrialization and urbanization of modern society are a serious problem. For example, conventional wastewater treatment technologies such as adsorption, coagulation, and filtration are expensive and cannot completely treat the discharge of organic pollutants in industrial wastewater. A promising alternative is the decomposition treatment of organic pollutants using an eco-friendly metal oxide photocatalyst. However, the rapid recombination of excited electron-holes limits the photolytic activity of semiconductor photocatalysts. This study investigates the inhibition of electron-hole recombination by supporting Ag nanoparticles on a ZnO photocatalyst. Ag/ZnO particles are generated under various conditions using ultrasonic spray pyrolysis. XRD analysis confirms the presence of Ag and ZnO crystal peaks in the generated particles. EDX mapping and STEM images show that Ag nanoparticles are well dispersed in ZnO. The photolysis rate of organic dye (rhodamine-B) is faster than that of ZnO in all Ag/ZnO particles, and particles with a 0.2 mass% silver nitrate supported on ZnO particles exhibit twice the photolysis activity of P25. Additionally, the optimal photolysis activity in 100 mL of 5 mg/L rhodamine-B aqueous solution with 10 mg of Ag/ZnO particles are confirmed and had excellent persistence and stability even during 7 reuses. [ABSTRACT FROM AUTHOR]