AZO Nanoparticles Research Articles

Synthesis of multifunctional flexible polymeric PVA/PEG blend nanocomposite films filled with AZO nanoparticles

Synthesis of multifunctional flexible polymeric PVA/PEG blend nanocomposite films filled with AZO nanoparticles

Flat-elongated-granulated complex morphology with (002) preferred orientation and high sinter activity of AZO nanoparticles by ethanol-assisted coprecipitation

Flat-elongated-granulated complex morphology with (002) preferred orientation and high sinter activity of AZO nanoparticles by ethanol-assisted coprecipitation

Structural and Optical Studies on Nanosized Thermoelectric Oxide-Zn1−xAlxO

Aluminum doped ZnO ([Formula: see text]AlxO, [Formula: see text], 0.02, 0.03 and 0.04) (AZO) nanoparticles were synthesized using citrate-gel method. We report the effect of aluminum doping along with variation of metal to citrate ratio on structural and optical properties of AZO nanoparticles with crystallite size optimization. The X-ray diffraction analysis confirmed Wurtzite crystal structure wherein the crystallite size was within the range of 15–40[Formula: see text]nm. Optical properties were studied with the help of UV-Visible spectroscopy. Bandgap calculated using Tauc plot is found to be between the range of 2.39–2.75[Formula: see text]eV and morphological analysis using Scanning Electron Microscopy (SEM) showed the distribution of synthesized material.

Enhanced Photocatalytic Performance of Al-Doped ZnO NPs-Reduced Graphene Oxide Nanocomposite for Removing of Methyl Orange Dye from Water Under Visible-Light Irradiation

In this work, a series of Al-doped ZnO nanoparticles-reduced graphene oxide (AZO–RGO) nanocomposites were successfully synthesized by loading AZO nanoparticles (AZO NPs) on the graphene oxide sheets via in situ and low temperature solvothermal method. Several techniques were utilized to characterize the resultant nanocomposites including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and FT-Infra Red (FT-IR) analyses. SEM and TEM studies showed that AZO NPs have been formed on RGO surface, confirming the formation of AZO–RGO nanocomposites. XPS, FT-IR, and XRD analyses revealed that the oxygen-containing functional groups can prepare as anchoring sites for capturing AZO NPs on RGO surface. Moreover, it was observed that these nanoparticles have wurtzite structure. The photo-catalysis results showed that the 5% AZO–RGO nanocomposite has a higher efficiency than that of pure ZnO and ZnO–RGO samples for removing methyl orange dye from water under visible light irradiation. The enhancement in the photocatalytic activity can be attributed to the increase of surface area of AZO–RGO nanocomposites in comparison with pure ZnO. Furthermore, the existing of Al dopants and RGO sheets in the prepared samples can effectively decrease the charge recombination process in the AZO–RGO nanocomposites.

Thermoluminescence properties of Al doped ZnO nanoparticles

ZnO nanoparticles doped with aluminum (AZO nanoparticles) were investigated using low temperature thermoluminescence (TL) and structural characterization experiments. TL experiments were performed on AZO nanoparticles in the temperature range of 10–300 K. TL curve presented one intensive peak around 123 K and two overlapped peaks to intensive peak around 85 and 150 K for heating rate of 0.1 K/s. Curve fitting and initial rise methods were used to find the activation energies of associated trapping centers. Analyses resulted in the presence of three centers at 0.05, 0.08 and 0.17 eV with peak maximum temperatures (Tm) of 86.2, 121.5 and 147.1 K, respectively. TL experiments were expanded using different heating rates between 0.1 K/s and 0.5 K/s. Behavior of revealed traps was investigated using an experimental technique called as Tm− Tstop method. It was seen that traps are quasi-continuously distributed within the band gap. Structural properties were studied using x-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy experiments.

Enhanced Ultraviolet Stability of Air-Processed Polymer Solar Cells by Al Doping of the ZnO Interlayer.

Photostability of organic photovoltaic devices represents a key requirement for the commercialization of this technology. In this field, ZnO is one of the most attractive materials employed as an electron transport layer, and the investigation of its photostability is of particular interest. Indeed, oxygen is known to chemisorb on ZnO and can be released upon UV illumination. Therefore, a deep analysis of the UV/oxygen effects on working devices is relevant for the industrial production where the coating processes take place in air and oxygen/ZnO contact cannot be avoided. Here we investigate the light-soaking stability of inverted organic solar cells in which four different solution-processed ZnO-based nanoparticles were used as electron transport layers: (i) pristine ZnO, (ii) 0.03 at %, (iii) 0.37 at %, and (iv) 0.8 at % aluminum-doped AZO nanoparticles. The degradation of solar cells under prolonged illumination (40 h under 1 sun), in which the ZnO/AZO layers were processed in air or inert atmosphere, is studied. We demonstrate that the presence of oxygen during the ZnO/AZO processing is crucial for the photostability of the resulting solar cell. While devices based on undoped ZnO were particularly affected by degradation, we found that using AZO nanoparticles the losses in performance, due to the presence of oxygen, were partially or totally prevented depending on the Al doping level.

Preparation and application of aluminum‐doped zinc oxide powders via precipitation and plasma processing method

ABSTRACTAluminum‐doped zinc oxide (AZO) conductive powders were successfully obtained through an attractive method based on the pyrolysis of coprecipitated precursors in arc plasma processing. The as‐prepared powders were characterized by the x‐ray diffraction (XRD), transmission electron microscopy (TEM), and UV‐vis spectrum. The results reveal that Al atoms are doped into ZnO lattice successfully and all the samples are polycrystalline with a hexagonal wurtzite structure. Moreover, the particle size of aluminum doped zinc oxide prepared from the plasma pyrolysis was smaller than conventional thermal calcination. Afterward, the synthesized powders were reinforced into polypropylene (PP) matrix and the dispersion of the AZO filler in the PP matrix was observed by SEM. In addition, the effect of AZO concentrations on the electrical and mechanical properties of PP composites was investigated via resistance measurement, tensile and impact tests, respectively. The results show that the electrical and mechanical properties depend on the concentration and dispersion of AZO nanoparticles in the matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41990.

Photochromic organic nanoparticles as innovative platforms for plasmonic nanoassemblies.

The fabrication of hybrid core-shell nanoassemblies involving a nondoped azo photochromic core coated with a dense shell of gold nanoparticles is reported to investigate the influence of localized plasmons onto the azo core photoisomerization. Photochromic organic nanoparticles, regarded as a novel class of high-density photoswitchable nanomaterials, are first elaborated upon precipitation in water of push-pull azo molecules, containing sulfur-terminated units to chelate gold nanoparticles. Photoisomerization studies of the azo nanoparticles reveal significantly higher E → Z photoconversion yields and Z → E thermal back relaxation rate constants compared to those of dyes processed as thin films and in solution, respectively. These unexpected results are ascribed to the large surface-to-volume ratio and cooperative effects encountered in nanoparticles that deform without disassembling under polarized illumination as a result of the weak change in the azo dipole moment. UV-vis spectroscopy and Raman microscopy of the hybrid nanoassemblies show strong optical coupling between both photoactive constituents, confirming that gold nanoparticles are tightly positioned on the azo core surface. Such coupling causes partial quenching of the azo photoisomerization but does not impact the thermal back relaxation. Longer sulfur-terminated chains provide reduced quenching of the photoreaction by the localized plasmons, thereby opening perspectives toward plasmon-mediated deformation of nano-objects for light-controlled nanomechanics.

Low-temperature crystal growth of aluminium-doped zinc oxide nanoparticles in a melted viscous liquid of alkylammonium nitrates for fabrication of their transparent crystal films

Highly transparent AZO films have been successfully fabricated via crystal growth of AZO nanoparticles in a melted isopropylammonium nitrate medium.

Structural investigation of aluminium doped ZnO nanoparticles by solid-state NMR spectroscopy

The electrical conductivity of aluminium doped zinc oxide (AZO, ZnO:Al) materials depends on doping induced defects and grain structure. This study aims at relating macroscopic electrical conductivity of AZO nanoparticles with their atomic structure, which is non-trivial because the derived materials are heavily disordered and heterogeneous in nature. For this purpose we synthesized AZO nanoparticles with different doping levels and narrow size distribution by a microwave assisted polyol method followed by drying and a reductive treatment with forming gas. From these particles electrically conductive, optically transparent films were obtained by spin-coating. Characterization involved energy-dispersive X-ray analysis, wet chemical analysis, X-ray diffraction, electron microscopy and dynamic light scattering, which provided a basis for a detailed structural solid-state NMR study. A multinuclear ((27)Al, (13)C, (1)H) spectroscopic investigation required a number of 1D MAS NMR and 2D MAS NMR techniques (T(1)-measurements, (27)Al-MQMAS, (27)Al-(1)H 2D-PRESTO-III heteronuclear correlation spectroscopy), which were corroborated by quantum chemical calculations with an embedded cluster method (EEIM) at the DFT level. From the combined data we conclude that only a small part of the provided Al is incorporated into the ZnO structure by substitution of Zn. The related (27)Al NMR signal undergoes a Knight shift when the material is subjected to a reductive treatment with forming gas. At higher (formal) doping levels Al forms insulating (Al, H and C containing) side-phases, which cover the surface of the ZnO:Al particles and increase the sheet resistivity of spin-coated material. Moreover, calculated (27)Al quadrupole coupling constants serve as a spectroscopic fingerprint by which previously suggested point-defects can be identified and in their great majority be ruled out.

Nanoscale azo pigment immobilized on carbon nanotubes via liquid phase reprecipitation approach

Nanoscale azo pigment immobilized on the outer shell of multiwalled carbon nanotubes (MWCNT–AZO) were prepared by modified liquid phase reprecipitation method, and the MWCNT–AZO hybrid was characterized by means of TEM, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–VIS absorption. The photoconductivity of single-layered photoreceptors, where MWCNT–AZO served as the charge generation material (CGM), was studied by the xerographic photoinduced discharge method. The results indicated that the MWCNT–AZO nano hybrid showed broader and enhanced photosensitivity than MWCNT/bulk azo pigments (AZO) blend or the bulk AZO did, which was interpreted in terms of nanometer size effect of MWCNT–AZO hybrid and charge transfer from AZO nanoparticles to MWCNT.

Preparation and photoconductivity study of azo nanoparticles via liquid phase surfactant-assisted reprecipitation

4,4′-bis(1′-Azo-2′-hydroxy-3′-naphthoyl-o-chloroanide) oxazole (AZO) nanoparticles in size of 40–60 nm were prepared by the method of liquid phase surfactant-assisted reprecipitation. The AZO nanoparticles were characterized by UV/VIS absorption, X-ray diffraction pattern, and TEM measurements. It revealed that AZO nanoparticles were near spherical in shape and were in amorphous state. The photoconductivity of AZO nanoparticles in single-layered photoreceptors was studied as well. The results showed that the photoconductivity of AZO nanoparticles was improved greatly compared to that of bulk AZO due to nanometer size effect.

Nanoscale azo pigment immobilized on carbon nanotubes via liquid phase reprecipitation approach

Nanoscale azo pigment immobilized on the outer shell of multiwalled carbon nanotubes (MWCNT–AZO) were prepared by modified liquid phase reprecipitation method, and the MWCNT–AZO hybrid was characterized by means of TEM, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–VIS absorption. The photoconductivity of single-layered photoreceptors, where MWCNT–AZO served as the charge generation material (CGM), was studied by the xerographic photoinduced discharge method. The results indicated that the MWCNT–AZO nano hybrid showed broader and enhanced photosensitivity than MWCNT/bulk azo pigments (AZO) blend or the bulk AZO did, which was interpreted in terms of nanometer size effect of MWCNT–AZO hybrid and charge transfer from AZO nanoparticles to MWCNT.