Iron Doped Zinc Oxide Research Articles

Influence of iron doping on morphological, structural and optical properties of zinc oxide thin films prepared by dip-coating method

Undoped zinc oxide and iron-doped zinc oxide thin films have been deposited by the sol-geldipcoating method. The Fe/Zn nominal volume ratio was 5% in the solution. The effects of Fe incorporation on morphological, structural, and optical properties of ZnO films were investigated. The scanning electron microscopy measurements showed that the surface morphology of the prepared thin films was affected by Fe doping. The X-ray diffraction patterns of the thin films showed that doped incorporation leads to substantial changes in the structural characteristics of ZnO thin films. The optical absorption measurements indicated a band gap in the range of 3.31 to 3.19 eV. The X-ray photoelectron spectroscopy demonstrated that Fe is incorporated in the ZnO matrix with 6.5 atomic percent (at %). The energy dispersive spectroscopy studies indicated the formation of ZnO with high efficiency.

Copper and iron doped zinc oxide: chemical synthesis, characterization and their properties

We report here the synthesis of Cu and Fe doped ZnO nano-particles. Cu and Fe doped ZnO nanoparticles were successfully synthesized and structurally, optically and morphologically characterized using X-ray diffractometer, optical spectroscope and scanning electron microscope. The crystal size is in the range of 15–20 nm for both the Cu and Fe doped ZnO nanoparticles. Nanoparticles are not below the critical size where quantum confinement effect is observed. ZnO has hexagonal, wurtzite structure. Synthesis was carried out at 60 °C. The light orange and gray color powder of Cu and Fe doped ZnO nanoparticles were obtained.

Bandgap narrowing of iron oxide nanotubes upon doping with zinc and their spectral sensitivity used as photoelectrode

ABSTRACTIron oxide nanotubes (NTs) and zinc doped iron oxide NTs were prepared by sol-gel method. Obtained NTs have spinel structure represented by ZnδFe3-δO4. Iron oxide NTs indicated a spectral sensitivity maximum at the wavelength of 500-550 nm and a long tail toward red light. These features were explained by a typical bandgap of iron oxide NTs to be ∼2.3 eV and bandgap narrowing for a small diameter NT. Organometal perovskite solar cell was constructed by using these NTs and evaluated by measuring the spectral sensitivity between the wavelength of 390 and 710 nm. For the present perovskite solar cell, drastic increase of the spectral sensitivity was obtained when we adjusted penetration depth of organometal perovskite into the porous layer of NTs. However, deep penetration worsened the spectral sensitivity. A similar trend was obtained for the cell using Zn doped iron oxide NTs, but the magnitude of incident power conversion efficiency (IPCE) became almost a half. This was explained by worsening the electrical conductivity, even the bandgap became narrower by Zn dope.

Sonochemically synthesized iron-doped zinc oxide nanoparticles: Influence of precursor composition on characteristics

Iron-doped zinc oxide nanoparticles have been synthesized sonochemically from aqueous acetyl acetonate precursors of different proportions. Synthesized nanoparticles were characterized with UV–vis spectroscopy, X-ray diffraction and microscopy. Influences of precursor mixture on the characteristics have been examined and modeled. Linear correlations have been proposed between dopant dosing, extent of doping and band gap energy. Experimental data corroborated with the proposed models.

Synthesis, characterisation and antimicrobial activity of manganese- and iron-doped zinc oxide nanoparticles

The present work reports study on antimicrobial activity of pure and doped ZnO nanocomposites. Polyvinyl pyrrolidone capped Mn- and Fe-doped ZnO nanocomposites were synthesised using simple chemical co-precipitation technique. The synthesised materials were characterised using transmission electron microscope (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV) visible spectroscopy. The XRD and TEM studies reveal that the synthesised ZnO nanocrystals have a hexagonal wurtzite structure with average crystalline size ∼7–14 nm. EDXRF and FTIR study confirmed the doping and the incorporation of impurity in ZnO nanostructure. The antimicrobial activities of nanoparticles (NPs) were studied against fungi, gram-positive and gram-negative bacteria using the standard disc diffusion method. The photocatalytic activities of prepared NPs were evaluated by degradation of methylene blue dye in aqueous solution under UV light irradiation. Experimental results demonstrated that ZnO NPs doped with 10% of Mn and Fe ions showed maximum antimicrobial and photodegradation efficiency in contrast with that of the 1% loading. The enhancement in antimicrobial effect and photocatalytic degradation is attributed to the generation of reactive oxygen species due to the synergistic effects of Mn and Fe loading.

Synthesis of iron-doped zinc oxide nanoparticles by simple heating: influence of precursor composition and temperature

We demonstrate a general single-pot heating method for preparing iron-doped zinc oxide nanocrystals from acetyl acetonate precursors in non-aqueous solvents. The particles were characterised by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), UV-visible (UV-Vis) and Fourier transform infrared (FTIR) optical absorbance spectroscopies. The dependences of the size of the nanocrystals and doping level on the synthesis temperature and precursor composition were elucidated and modelled.

Fabrication and characterization of a highly sensitive hydroquinone chemical sensor based on iron-doped ZnO nanorods.

Herein, we report the development of a simple and highly sensitive hydroquinone (HQ) chemical sensor based on an electrochemically activated iron-doped (Fe-doped) zinc oxide nanorod (ZnO NR) modified screen-printed electrode (SPE). The Fe-doped ZnO NRs were prepared using a hydrothermal process and their morphological, crystal, compositional and optical properties were characterized in detail. The detailed characterizations showed that the NRs are densely grown, well-crystalline and possess a wurtzite hexagonal phase. The fabricated HQ electrochemical sensor exhibited high sensitivity of 18.60 μA mM(-1) cm(-2) and a very low experimental detection limit of 0.51 μM. Our results demonstrate that simply prepared doped ZnO nanomaterials are promising candidates to fabricate highly sensitive electrochemical sensors.

Structure and Electronic States of Zinc-Doped Iron Oxide Nanotubes Prepared by a Surfactant-Assisted Sol–Gel Method

We report the doping of iron oxide nanotubes with zinc, and the characterization of the resulting zinc ferrite nanotubes. Gels were prepared by polycondensing iron nitrate nonahydrate and zinc nitrate hexahydrate on the surface of a self-assembled non-ionic surfactant in 1-propanol at 45 °C. Evaporation of the solvent within the gels at 120 °C led to the formation of tubular structures, as evidenced by transmission electron microscopy. The nanotubes had internal and external diameters of ~2–6 and 4–10 nm, respectively, and were ~50 nm long. X-ray diffraction and X-ray photoelectron spectroscopy indicated that the nanotubes possessed a spinel structure, and had a composition of ZnxFe3−xO4, with x ranging from 0 to 0.66. Direct band gaps were evaluated from optical absorption spectra, using the Tauc plot method. The band gaps ranged from 2.4 (x = 0) to 2.0 eV (x = 0.27), thus narrowing upon doping with Zn. This was tentatively attributed to a widening of the band width, and the formation of sub-levels at octahedral B sites of the spinel structure.

A soil mediated phyto-toxicological study of iron doped zinc oxide nanoparticles (Fe@ZnO) in green peas (Pisum sativum L.)

• This is the first study on the impacts of Fe@ZnO NPs in terrestrial plants. • At 500 mg/kg, Fe@ZnO NPs reduced chlorophyll (27%) and ROS production (∼50%) compared to control. • Fe@ZnO NPs showed less phytotoxic effects compared to bare ZnO NPs. • At all concentrations Fe@ZnO NPs decreased APOX activity (33–86%) in all tissues. • At 500 mg/kg, Fe@ZnO NPs increased catalase activity in roots (30%) and leaves (400%). Iron doping has shown to reduce toxicity of zinc oxide nanoparticles (ZnO NPs) in several organisms. To the best of authors’ knowledge, this is the first report on toxicological studies of Fe@ZnO NPs on terrestrial plants. In this study, green pea plants ( Pisum sativum L.) were grown for 25 days in soil treated with 10% Fe@ZnO NPs at 0–500 mg/kg. Effects were compared with our previous study where phytotoxicity of bare-ZnO NPs had been investigated on green pea plants grown under similar environmental conditions. Different physiological and biochemical growth parameters were measured. Results showed increased Zn bioaccumulation in roots (200%) and stems (31–48%) as the exposed NP concentration increased ( p ⩽ 0.05) but Fe absorption was not affected. At 500 mg/kg Fe@ZnO NPs treatment, chlorophyll content (27%) and H 2 O 2 production (∼50%) decreased significantly ( p ≤ 0.05) compared to control. Toxicity of doped ZnO NPs is less than that of bare ZnO NPs as per zinc uptake, chlorophyll content, and ROS (H 2 O 2 ) production are considered. Therefore, iron doping can be considered as a safer approach to reduce toxicity of ZnO NPs in terrestrial plants.

Enhanced visible-light photocatalytic activity of Fe/ZnO for rhodamine B degradation and its photogenerated charge transfer properties

Zinc oxide (ZnO) and iron doped zinc oxide (Fe/ZnO) nanoflowers were successfully synthesized via a simple hydrothermal process. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman scattering, ultraviolet–visible (UV–vis) diffuse spectroscopy and scanning electron microscopy (SEM), and it was found that the dopant ions replaced some of the crystal lattice zinc ions, and furthermore, Fe3+ and Fe2+ ions coexist. Photocatalytic activities of the catalysts were assessed based on the degradation of rhodamine B (RhB) in aqueous solution under both UV and visible light irradiation (λ>420nm), respectively. All Fe/ZnO samples showed enhanced photocatalytic activity under the irradiation of visible light. On the contrary, Fe/ZnO products displayed poorer performance than that of pure ZnO in the presence of UV light. This phenomenon can be attributed to the coexistence of Fe3+ and Fe2+ in the ZnO host. The photophysical mechanism of the UV and visible photocatalytic activity was investigated with the help of surface photovoltage (SPV) and PL measurements, respectively. The results indicated the influence of coexistence of Fe3+ and Fe2+ in ZnO host on the separation and transfer behavior of the photogenerated charges in the UV and visible regions, which are distinctly different: under the irradiation of UV light, the recombination of the photogenerated electrons and holes was promoted, whereas the separation and transfer of photogenerated electrons and holes was facilitated under the visible light irradiation. The detailed photocatalytic mechanism and the role of Fe on the photodegradation process are discussed.

Photocatalytic Oxidation of Dye Bearing Wastewater by Iron Doped Zinc Oxide

In the present study, photocatalytic oxidation of dye bearing wastewater has been done using iron doped zinc oxide (Fe/ZnO) photocatalyst. Various photocatalysts were synthesized by solution combustion synthesis method, and their structural, morphological, and optical properties were studied using N2 adsorption–desorption, Fourier transform infrared spectroscopy, X-ray diffractometer, thermogravimetric analysis, field emission scanning electron microscope, transition electron microscope, and UV–visible diffuse reflectance spectra. Effect of various parameters such as the amount of iron doped, calcination temperature, calcination time, pH of the dye solution, catalyst dose, hydrogen peroxide dose, reaction temperature, and initial concentration of the dye solution were optimized. At optimum conditions, more that 71% color removal, 94% dye degradation, and 41% total organic carbon removal was observed for acid red 1 dye solution having an initial concentration of 50 mg/L and initial color of 2730 Pt:Co units.

Photoinduced Atom Transfer Radical Polymerization Using Semiconductor Nanoparticles

Photoinduced atom transfer radical polymerization of methyl methacrylate initiated by in situ generation of copper (I) complex from higher oxidation state species using neat zinc oxide and iron-doped zinc oxide nanoparticles is investigated. The polymerizations proceed in a well-controlled manner under UV light at room temperature as evidenced by kinetic and light on-off experiments. The evolution of molecular weight with conversion shows good correlations between experimental and theoretical molecular weights, which confirmed good control over polymerization along with a narrow molecular weight distribution.

Room temperature ferromagnetism in combustion reaction prepared iron-doped zinc oxide nanoparticles

We present a study of the structural and magnetic properties of Zn1−xFexO (0.00≤x≤0.09) nanoparticles prepared by a combustion reaction method. X-ray diffraction patterns of all samples showed sharp and intensive peaks of hexagonal wurtzite structure of ZnO without any evidence of spurious crystalline phases in all samples. The magnetic properties were measured by using a vibrating sample magnetometer. Hysteresis loop indicated that all samples are ferromagnetic at room temperature and the Curie temperature increased with increasing iron content. Room temperature ferromagnetism can be explained in terms of intrinsic properties and the presence of defects in Fe- doped ZnO nanoparticles.

Ferromagnetism of zinc oxide nanograined films

The reasons for the appearance of ferromagnetic properties of zinc oxide have been reviewed. It has been shown that ferromagnetism appears only in polycrystals at a quite high density of grain boundaries. The crit� ical size of grains is about 20 nm for pure ZnO and more than 40 µm for irondoped zinc oxide. The solubility of manganese and cobalt in zinc oxide increases significantly with a decrease in the size of grains. The depen� dences of the saturation magnetization on the concentrations of cobalt, manganese, and ion are nonmono� tonic. Even if the size of grains is below the critical value, the ferromagnetic properties of zinc oxide depend significantly on the texture of films and the structure of amorphous intercrystallite layers.

In vivo pulsed magneto-motive ultrasound imaging using high-performance magnetoactive contrast nanoagents.

Previously, pulsed magneto-motive ultrasound (pMMUS) imaging has been introduced as a contrast-agent-assisted ultrasound-based imaging modality capable of visualizing biological events at the cellular and molecular level. In pMMUS imaging, a high intensity pulsed magnetic field is used to excite cells or tissue labeled with magnetic nanoparticles. Then, ultrasound (US) imaging is used to monitor the mechanical response of the tissue to an externally applied magnetic field (i.e., tissue displacement). Signal to noise ratio (SNR) in pMMUS imaging can be improved by using superparamagnetic nanoparticles with larger saturation magnetization. Metal-doped magnetic nanoparticles with enhanced tunable nanomagnetism are suitable candidates to improve the SNR and, therefore, sensitivity of pMMUS imaging, which is essential for in vivo pMMUS imaging. In this study, we demonstrate the capability of pMMUS imaging to identify the presence and distribution of zinc-doped iron oxide nanoparticles in live nude mice bearing A431 (human epithelial carcinoma) xenograft tumors.

Enhanced photocatalytic activity of iron doped zinc oxide nanowires for water decontamination

Zinc oxide (ZnO) and iron doped zinc oxide (ZnO/Fe) nanowires were synthesized on glass substrates through a conventional hydrothermal method and the nanowires were characterized by UV–visible spectrum, scanning electron microscope (SEM), X-ray diffraction (XRD), and Raman spectroscopy techniques, respectively. Photocatalytic activities of ZnO and ZnO/Fe nanowires were investigated in both UV and white light for degradation of organic contaminants (1, 2-dichlorobenzene ‘DCB’ and methyl orange ‘MO’) in water. The ZnO/Fe nanowires exhibit an improved photocatalytic activity compared to ZnO nanowires. The photocatalytic performance of the nanowires is also compared to P25 titanium oxide (TiO2) for degradation of DCB and MO. Interestingly, ZnO/Fe nanowires show superior photocatalytic activity than TiO2 in white light and a similar activity level under UV light. The results indicate that this photocatalyst is suitable for the decontamination of organic materials under solar radiation.

A magnetic switch for the control of cell death signalling in in vitro and in vivo systems

The regulation of cellular activities in a controlled manner is one of the most challenging issues in fields ranging from cell biology to biomedicine. Nanoparticles have the potential of becoming useful tools for controlling cell signalling pathways in a space and time selective fashion. Here, we have developed magnetic nanoparticles that turn on apoptosis cell signalling by using a magnetic field in a remote and non-invasive manner. The magnetic switch consists of zinc-doped iron oxide magnetic nanoparticles (Zn(0.4)Fe(2.6)O(4)), conjugated with a targeting antibody for death receptor 4 (DR4) of DLD-1 colon cancer cells. The magnetic switch, in its On mode when a magnetic field is applied to aggregate magnetic nanoparticle-bound DR4s, promotes apoptosis signalling pathways. We have also demonstrated that the magnetic switch is operable at the micrometre scale and that it can be applied in an in vivo system where apoptotic morphological changes of zebrafish are successfully induced.

Catalytic Degradation of Reactive Golden Yellow CRL Using Iron Doped Zinc Oxide

Iron-doped Zinc oxide, synthesized using wet chemical technique, was employed to degrade a commonly used textile dye namely Reactive Golden Yellow dye CRL in order to assess the effectiveness and feasibility of the catalyst towards degradation. The degradation efficiency was evaluated by studying the effects of parameters like initial dye concentration (0.05-0.25mg), catalyst amount (0.1-1.0g), temperature (25-100°C), pH (1-14) and contact time (10-120min). The percentage degradation was calculated from residual concentration spectrophotometrically. It was found that optimum degradation was obtained using 0.5g of the catalyst and maintaining temperature and pH at 85oC and 5, respectively for the contact time of 60min.

Noninvasive Remote-Controlled Release of Drug Molecules in Vitro Using Magnetic Actuation of Mechanized Nanoparticles

Mesoporous silica nanoparticles are useful nanomaterials that have demonstrated the ability to contain and release cargos with mediation by gatekeepers. Magnetic nanocrystals have the ability to exhibit hyperthermic effects when placed in an oscillating magnetic field. In a system combining these two materials and a thermally sensitive gatekeeper, a unique drug delivery system can be produced. A novel material that incorporates zinc-doped iron oxide nanocrystals within a mesoporous silica framework that has been surface-modified with pseudorotaxanes is described. Upon application of an AC magnetic field, the nanocrystals generate local internal heating, causing the molecular machines to disassemble and allowing the cargos (drugs) to be released. When breast cancer cells (MDA-MB-231) were treated with doxorubicin-loaded particles and exposed to an AC field, cell death occurred. This material promises to be a noninvasive, externally controlled drug delivery system with cancer-killing properties.

Magnetic nanobelts of iron-doped zinc oxide

Magnetic nanobelts of iron-doped zinc oxide were fabricated by vapor–phase transport using zinc oxide, iron oxide, and graphite as source materials. The nanobelts grew mainly along [101¯0] orientation and enclosed by ±(0001) and ±(1¯21¯0) surfaces. The measurements of x-ray diffraction, energy-dispersive x-ray spectroscopy, and high-resolution transmission electron microscopy demonstrated that iron was doped into the nanobelts. As a result, the nanobelts were magnetic.