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• Ozone treated ZnO surface analysed in term of crystallinity, and structure by SEM and XRD. • Charge transport in ozone treated ZnO surface studied by ultrafast transient absorption spectroscopy. • Comparison of the electrical parameter of the organic solar cell under different ozone treatment time. • Defect state and its impact on performance of organic solar cell identified using capacitance spectroscopy. Zinc oxide (ZnO) has great potential as an electron transport layer (ETL) for producing efficient and stable organic solar cells. The effect of ozone treatment on ZnO working as the ETL in the organic solar cell has been studied by analyzing crystallinity, the defect density of states, and charge carrier dynamics from transient absorption spectroscopy to understand its role in the improvement in the interface between ETL and active layers. We have observed that a 10-minute continuous ozone treatment of ZnO film demonstrates improvement in its crystallinity leading to a 23% increment in short circuit current. The improvement in the crystallinity has been confirmed by the morphological and structural analysis using SEM and GIXRD. These analyses reveal the formation of a flake-like structure and an increase in peak intensity in GIXRD. It has been observed that ozone exposure has significantly affected the carrier recombination resistance, ideality factor of the device. From transient absorption spectroscopy, it has been found that for 10 min ozone-treated ZnO film has an average carrier transport time (661.79 ps), which is smallest as compared to untreated film or over treated film leading to faster carrier extraction through ETL. Further, the study of defect density of states shows that optimized ozone-treated film show 22.08% decrease in defects as compared to the control device, which primarily reflected as the improvement in the current density leading to increase in device efficiency from 2.95% to 3.75%. [ABSTRACT FROM AUTHOR]

Abstract: We report the magnetoelectric, dielectric and magnetic properties of xCo0.7Zn0.3Fe2O4–(1− x)Bi0.9La0.1FeO3 (x =0.1, 0.2, 0.3 and 0.4) nanocomposites prepared by sol–gel method. The X-ray diffraction patterns of sintered pellets show the formation of composite phases. The average crystallite size obtain by Williamson–Hall plot for different nanocomposites were found to be in the range 70–80nm, which are in agreement with particle size calculated from atomic force microscopy. Magnetoelectric voltage coefficient (α E =315mV/cmOe) and the magnetocapacitance (MC=3.1%) for x =0.3 were found to be higher than other synthesized nanocomposites. [Copyright &y& Elsevier]

Abstract: Thermally evaporated ZnO thin films have been irradiated with 100MeV Au8+ ions at different fluence from 5×1011 ions/cm2 to 5×1013 ions/cm2. The optical and structural properties of the irradiated and pristine films were studied using Fourier transform infrared spectroscopy (FTIR), UV–visible absorption spectroscopy, photoluminescence (PL), atomic force microscopy (AFM) and XRD. FTIR results showed that for low fluence, the transmittance of the film decreased and increased again at higher fluence but Zn–O bond remains unaffected by irradiation. As revealed from the absorption spectra, absorption edge is not changed by the irradiation but the optical absorption is increased. The AFM study of the films implied that roughness decreased at low fluence values up to 5×1012 ions/cm2 and at higher fluences the roughness increased. [Copyright &y& Elsevier]

The control of polarization rotation (PR) is a key issue of applying undoped zinc oxide (ZnO) as information storage devices. A systematic study of ZnO thin films by conducting piezoresponse force microscopy (PFM) technique on samples with different electrodes, film thicknesses, and deposition oxygen partial pressures, P O 2 allows disclosing the possible factors those affecting the PR behavior. The results clearly indicate that higher work function conductive material, such as Pt, is a promising candidature as the top electrode and bottom electrode to ensure the PR occur and maintain in ZnO films. From the effects of film thickness study, PR behavior can be observed in film downscaled to 15 nm. However, in order to avoid current leakage and maintain the rotated polarization state, thicker film with about 240 nm is preferred. In addition, in the film deposited with a low P O 2 (>5 × 10−6 Torr), more atomic point defects such as oxygen vacancy may lead the sample into a large leakage current and deteriorate the PR behavior. Hence, by this systematic study, it is proved that the PR behavior of undoped ZnO thin films can be optimized with proper deposition parameters. Image 1 • Possible factors affecting the PR behavior are studied comprehensively. • Pt is a promising electrode candidature for PR behavior comparing with Au and ITO. • Unambiguous PR behavior is found in film with a thickness reduced to 15 nm. • P O 2 below 5 × 10−6 Torr might hinder the PR behavior. [ABSTRACT FROM AUTHOR]

In recent times cost-effective advanced materials with dual applications in photocatalytic water treatment and electrochemical sensing have been explored and developed. Herein we report facile solution combustion synthesis of ZnO/Fe 2 O 3 (ZF) type-II heterojunction for electrochemical sensing of dopamine and visible assisted photocatalytic reduction of carcinogenic Cr(VI) into Cr(III). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to evaluate the compatibility of the electrodes for DA sensing. Furthermore, DPV curves revealed that ZF2 (ZnO: Fe 2 O 3 - 3:0.5) modified GCEs possessed 0.27 μM and 0.7 μM of LOD and LOQ with good linear range from 3 μM to 30 μM. Overall, reproducibility and interference studies confirm the efficient use of material for DA sensing. The junction ZF2 shows best performance with 88% Cr(VI) photo-reduction under visible light in 90 min and 100% reduction with tartaric acid as sacrificial agent (utilizing holes) in just 45 min. The effect of sacrificial agents and scavengers suggest the photogenerated electrons were major active species followed by ●O 2 −. The CB edges have enough potential for rapid reduction of hexavalent chromium under visible light and solar light. The photoluminescence and electrochemical impedance suggest lowered recombination, high charge separation and charge transfer capacity in the heterojunction. The transfer of electrons from conduction band of Fe 2 O 3 to that of ZnO having high enough negative potential to reduce Cr(VI), thus utilizing the CB potential of wide band gap ZnO for rapid visible photocatalysis. In addition shortcomings as low conductivity Fe 2 O 3 and high band gap of ZnO are both minimized in the junction. This study confirmed that popular semiconductors as ZnO and Fe 2 O 3 have enough potential in dual role as electrochemical sensors and visible photocatalysts with best performance by optimizing the conditions and ratios. Image 1 [ABSTRACT FROM AUTHOR]

The influence of Ga dopant on resistive switching behavior of ZnO-nanorods film conducting bridge random access memory was investigated. Using a hydrothermal process, we grew vertically well-aligned and uniform Ga doped ZnO (GZO)-NRs films on transparent glass substrates to fabricate Cu/TiW/GZO-NRs/Indium Tin Oxide/Glass devices. The GZO-NRs film provides a diffusion path for the Cu ions to form a conducting bridge; thus, reducing the formation of a branched filament. The Ga dopant induces a significant improvement in switching distribution of high resistance states (HRS) and low resistance states (LRS). The 1.5 mol% Ga doped device exhibits good retention up to 10 4  s and high HRS/LRS ratio of 30 times. Therefore, our proposed device structure may be a good candidate for future conductive-bridge resistive random access memory application. [ABSTRACT FROM AUTHOR]

In precedent work, nano-ZnO was supported on activated carbon or brick grain particles using simple co-precipitation method. Successful formation of ZnO-activated carbon (ZnO-AC) and ZnO-brick grain particle (ZnO-BGP) nanocomposites was ascertained by various spectral techniques. Scanning electron microscope (SEM) images revealed that ZnO particles were highly dispersed in activated carbon/brick grain particles. The size of ZnO-AC and ZnO-BGP was found to be 70 and 80 nm, respectively. Both ZnO-AC and ZnO-BGP exhibited excellent adsorption and photocatalytic activity for malachite green (MG) and congo red dye (CR) degradation. The adsorption data for MG and CR removal followed pseudo second order kinetic model. The adsorption capacity followed the order: ZnO-AC > ZnO-BGP > ZnO. The effect of adsorption on photocatalysis was explored under different reaction conditions. Simultaneous adsorption and photocatalysis (A + P) exhibited promoting effect on dye degradation. While adsorption followed by photocatalysis (A − P) had retarding effect on dye removal. ZnO-AC/A + P system emerged as highly efficient for MG and CR degradation. The rate of photodegradation followed pseudo first order kinetics. Using ZnO-AC/A + P system, 99 and 92% of COD removal was attainted for MG and CR degradation, respectively. The oxidative degradation mainly occurred through hydroxyl radicals. The prepared nanocomposites possessed higher recyclability and could be easily separated from solution by sedimentation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fe doped ZnO nanoparticles have been successfully synthesized by simple sol–gel route. [•] Solubility limit of Fe in ZnO matrix is found to be less than 5%. [•] Fe doped ZnO nanoparticles are better photocatalytic activist than ZnO. [•] Prepared particles possess intrinsic room temperature ferromagnetism. [ABSTRACT FROM AUTHOR]

Abstract: Thin films with ZnO nanocrystals in silica were synthesized by rf reactive magnetron co-sputter deposition and post-annealing. The films were deposited from a ZnO/Si composite target in an rf oxygen plasma. The deposited films were annealed in air/vacuum at high temperatures to grow ZnO nanocrystals. The deposited and annealed films were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), uv–vis spectroscopy (UV–VIS) and photoluminescence (PL) measurements. FT-IR results of the films show the vibrational features of Si–O–Si and Zn–O bonds. UV–VIS spectra of the deposited film shows the band edge of ZnO. The XRD results of the films annealed at 750°C and 1000°C indicate the growth of ZnO nanocrystals with average crystallite sizes between 7nm and 26nm. PL measurements of the deposited film show a broad visible luminescence peak which can be due to ZnO. These results suggest the growth of ZnO nanocrystals in silica matrix. [Copyright &y& Elsevier]

Pectin-guar gum-zinc oxide (PEC-GG-ZnO) nanocomposite was prepared by precipitation technique. The composite was characterized by using FT-IR, XRD, HRTEM, SAED, EDS, and SEM. TEM images showed the hexagonal shape of nanocomposite with the size range of 50–70 nm. Further, PEC-GG-ZnO was used as an immunomodulator for the first time to improve the cancer cells killing capabilities of human peripheral-blood lymphocytes (PBL). The lymphocyte proliferation assay proved the immunostimulatory property of the PEC-GG-ZnO which increased with the increase in concentration (25 μg/ml to 200 μg/ml). ELISA detection confirmed a significant increase in the release of IFN-γ, IL-2 and TNF-α cytokines and flow cytometry analysis revealed enhanced expression of CD3, CD8, and CD56 after treating PBL with PEC-GG-ZnO as compared to PEC and GG treatment. Moreover, we also found that nanocomposite pretreated human PBL displayed enhanced cytotoxicity towards lung (A549) and breast carcinoma (MCF-7) cells as compared to untreated PBL. The microcytotoxicity assay also demonstrated that with increase in effector: target ratios from 2.5:1 to 20:1, there was an increase in the cancer cell death. Taken together, the current data corroborates the immunostimulatory activities of PEC-GG-ZnO, a novel nanocomposite, hence it can serve as a promising cancer therapeutic agent. [ABSTRACT FROM AUTHOR]

Currently, the photocatalytic nanomaterials performing under solar radiation have gained worldwide attentions due to increasing environmental deterioration. For utilizing the sunlight for degradation of emerging pollutants it is important to develop visible active photocatalysts. This laboratory scale work reports magnetic and optically active nano-photocatalyst Fe x Zn 1−x O(x = 0.01, 0.03, 0.05) synthesized by solution combustion method. High resolution transmission microscopy suggests a slight degradation in the crystallite structure with Fe doping. X-ray photoelectron spectroscopy analysis shows the presence of intrinsic defects in the crystal structure. Zn resides in +2 and and Fe in +3 oxidation state. Optical band gap studies were made with band structure for each doped sample. The photoctalytic activity of the samples was tested by solar degradation of noxious pollutant Bisphenol A. 99.1% of bisphenol was degraded in 90min in presence of Fe 0.03 Zn 0.97 O under synergistic adsorption and photocatalysis. The results were analyzed in terms of total organic carbon, chemical oxygen demand, effect of scavengers, gas chromatography-mass spectrometry and reusability. In presence of Fe 0.03 Zn 0.97 O, 45.3% of total organic carbon was removed and chemical oxygen demand was reduced to 11.2%. A possible mechanism with structures of the intermediates has been given. Effect of scavengers reveal that hydroxyl radicals are major reactive oxygen species involved which is also supported by the band edge positions. The research work promises to design highly photo-active tuneable magnetic photocatalysts for solar powered degradation of contaminants of emerging concern with a simple and cost-effective approach. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel nanocomposite Fe0.01Ni0.01Zn0.98O/polyacrylamide was synthesized. [•] FNZP/PAM nanocomposite shows good degradation efficiency for MB and MG. [•] Rapid decolouration of dyes was observed under coupled adsorption and photocatalysis. [•] Dye degradation followed the pseudo first-order kinetics. [•] A higher recycle efficiency and antibacterial activity was achieved for nanocomposite. [Copyright &y& Elsevier]