Co-doped ZnO Nanoparticles Research Articles

Structural, optical and enhanced antibacterial activities of ZnO and (Co, Fe) co-doped ZnO nanoparticles by sol-gel combustion method

Zn1-x(Co, Fe)xO nanoparticles (NPs) were synthesized by sol-gel combustion method.XRD pattern confirmed the formation of single-phase hexagonal (wurtzite) structure in all samples withP63mcspace group.The average crystallite sizes varied between 20 and 28 nm. All samples were optically activated under ultraviolet light. The optical band gap values varied between 3.33 and 3.82 eV. The PL study revealed the reduction of the recombination of charge carriers due to (Co,Fe) co-doping into ZnO. Enhancement of the antibacterial activity was observed due to (Co,Fe) co-doping. Zn0.95Co0.025Fe0.025NPs exhibited excellent antibacterial activity against E. coli and S. aureus bacteria.

Electrical conductivity improvement of (Fe + Al) co-doped ZnO nanoparticles for optoelectronic applications

Electrical conductivity improvement of (Fe + Al) co-doped ZnO nanoparticles for optoelectronic applications

(Co, Mn) co-doped ZnO nanoparticles and application in quantum dot sensitized solar cells

Here, we synthesized the pure ZnO and (Co 2 % and Mn x%) co-doped ZnO nanoparticles using co-precipitation method. The structural, optical, and morphological properties were optimized by varying concentration of Mn dopants. Using photoluminescence (PL) study, the chromaticity plots were incorporated in the study. Prepared samples have potential to be utilized in optoelectronic devices because of their distinct properties. These samples were used as an active layer material in photoanode of CdS/CdSe QD based solar cells. QDSSC based on C2M4 ZnO nanocrystals exhibited superior short circuit current density (5.813 mA cm−2) and photo conversion efficiency (1.0798 %) than pristine ZnO based QDSSC (2.798 mA cm−2, 0.5047 %). Future perspectives are provided to discuss further strategies for enhancing the photovoltaic efficiency of QDSSCs.

Functional Properties of Donor (Al) and Acceptor (Cu) Codoped High Dielectric Constant ZnO Nanoparticles

In this work, we have synthesized donor‐acceptor (Al‐Cu) codoped ZnO nanoparticles with a doping concentration of 0%, 0.25%, 0.5%, and 0.75% by coprecipitation method. The synthesized samples were then annealed at 350°C and 600°C. All the samples showed wurtzite structure of ZnO with no secondary phase. The increase in doping concentration led to deterioration of crystalline quality, while improved crystallinity was observed at higher annealing temperature. The morphological study of these samples showed good grain‐to‐grain contact with less isolated pores. These samples were further characterized by impedance spectroscopy for analyzing dielectric properties. The values of the real part of dielectric constant and tangent loss showed decreasing trend with frequency. The appearance of semicircular arcs in the impedance complex plane plots indicates contribution of grains and grain boundaries and presence of different relaxation processes. 0.5% Al and Cu codoped ZnO showed the best dielectric response with a high value of dielectric constant and low tangent loss.

Effect of Annealing Temperature on the Properties and Photocatalytic Efficiencies of Ti/Ga Co-Doped Zno Nanoparticles

Effect of Annealing Temperature on the Properties and Photocatalytic Efficiencies of Ti/Ga Co-Doped Zno Nanoparticles

Effect of Annealing Temperature on the Properties and Photocatalytic Efficiencies of Ti/Ga Co-Doped Zno Nanoparticles

Effect of Annealing Temperature on the Properties and Photocatalytic Efficiencies of Ti/Ga Co-Doped Zno Nanoparticles

Green Synthesis of Cu-Mn Co-Doped Zno Nanoparticles for Antimicrobial and Photocatalytic Applications

Green Synthesis of Cu-Mn Co-Doped Zno Nanoparticles for Antimicrobial and Photocatalytic Applications

Green Synthesis of Cu-Mn Co-Doped Zno Nanoparticles for Antimicrobial and Photocatalytic Applications

Green Synthesis of Cu-Mn Co-Doped Zno Nanoparticles for Antimicrobial and Photocatalytic Applications

Plasma assisted synthesis of cobalt-doped ZnO nanoparticles in liquid

Cobalt-doped ZnO nanoparticles were synthesized by electrical discharge treatment of a mixture of metallic zinc and cobalt micropowders (with Co atomic concentration of 10%) in distilled water. The results of the characterization of inner structure, phase composition and morphology of the prepared samples performed by means of TEM, XRD, FTIR and UV–Vis spectroscopy proved the formation of near-spherical doped ZnO:Co nanocrystals under the found optimized experimental conditions. The band gap of the Co-doped ZnO nanoparticles was estimated to be 2.88 eV in comparison to the pure ZnO – 3.28 eV. The broad luminescence band associated with the formation of defect levels in Co-doped ZnO was observed the range from 450 nm to 750 nm. The prepared Co-doped ZnO nanocrystals exhibited ferromagnetic behavior at room temperature that can be useful for their application in spintronics.

Robust ferromagnetism in rare-earth and transition metal co-doped ZnO nanoparticles for spintronics applications

This work reports on the robust ferromagnetism at room temperature in co-precipitation derived rare-earth (Tb) and transition metal (Co) co-doped ZnO nanoparticles (NPs). X-ray diffraction (XRD) analysis reveals the single-phase character. Morphological studies confirm the formation of spherical-shaped particles with different orientations separated by well-defined grain boundaries. The increase in oxygen vacancies is confirmed by photoluminescence (PL) spectra. The (Tb, Co) co-doped NPs exhibit room temperature ferromagnetic (RTFM) behavior, which has been discussed based on oxygen vacancies mediated magnetic polarons and the effect of grain boundaries.

The role of Co in doping ZnO nano-particles in enhancement the structural, optical and magnetic properties for spintronics

Zn1−xCoxO (0 ≤ x ≤ 0.10) nano-particles were fabricated successfully via ball milling procedure. The influence of [Co]/[Zn] on the properties of nano-particles was examined employing X-ray diffraction, the energy dispersion of the X-ray (EDX), Scan Electron Microscope (SEM), these measurements exhibit the growth hexagonal wurtzite crystal phase Zn1−xCoxO nano-particles with the successfully incorporation of Co+2 ions in the ZnO lattice. The optical characterization investigated utilizing Ultraviolet-Visible (UV) absorption spectroscopy for Zn1−xCoxO nano-particles refers to a red-shift in the optical bandgap with increasing Co ion inside ZnO matrix, this result confirm the bandgap is considerably narrowed with increasing Co ratio. The measurements of magnetization applying vibrating sample magnetometer illustrated a hysteresis loop in Co-doped ZnO nano-particles. Thanks to the variation values of bandgap Eg opt and magnetic measurements of ZnO nano-particles doped Co% plays a major role for selective coatings of optoelectronics; use as antireflective coating materials, and fabrication of optoelectronic devices.

Effect of Al and Mg Doping on Reducing Gases Detection of ZnO Nanoparticles

In this work, the main objective is to enhance the gas sensing capability through investigating the effect of Al and Mg doping on ZnO based sensors. ZnO, Mg1% doped ZnO, Al5% doped ZnO and (Al5%, Mg1%) co-doped ZnO nanoparticles (NPs) were synthesized by a modified sol-gel method. The structural characterization showed the hexagonal crystalline structure of the prepared samples. Morphological characterizations confirmed the nanometric sizes of the NPs (27–57 nm) and elemental composition investigation proved the existence of Al and Mg with low concentrations. The optical characterization showed the high absorbance of the synthesized samples in the UV range. The gas sensing performances of the synthesized samples, prepared in the form of thick films, were investigated. Sensing tests demonstrated the high influence of the Al and Mg on the sensing performances towards H2 and CO gas, respectively. The 5A1MZO-based sensor exhibits high sensitivity and low detection limits to H2 (<2 ppm) and CO (<1 ppm). It showed a response around 70 (at 250 °C) towards 2000 ppm H2 and 2 (at 250 °C) towards CO.

Structural, Optical and Magnetic Properties of (Al, Ni) Co-Doped ZnO Nanoparticles

In the present work, the synthesis of Zn0.9_xNi0.1AlxO (x = 0.01, 0.015, 0.02 and 0.025) nanoparticles by sol–gel and theirs structural, optical and magnetic properties were investigated. In our approach, we performed a drying under supercritical conditions of ethyl alcohol. An esterification reaction was established to release water slowly. The powder obtained underwent a heat treatment in air at 500 °C in 2 hours. The results obtained by X-rays diffraction (XRD) and transmission electronic microscopy (TEM) showed that the structure is wurtzite with a crystallite size ranging from 25 nm to 40 nm, and a second phase was detected, linked to the NiO phase. Ultraviolet-visible (UV-Vis) spectroscopy shows a decrease in bandgap values with increasing of Al concentration. Photoluminescence (PL) results indicate the effects of oxygen vacancies on emission spectra. Magnetic measurements at 300 K and 10 K showed a paramagnetic with an improve of ferromagnetic at low temperature.

Enhanced Photocatalytic and Photoluminescence Properties of Ce and Dy Co-Doped ZnO Nanoparticles

Enhanced Photocatalytic and Photoluminescence Properties of Ce and Dy Co-Doped ZnO Nanoparticles

Co-Doped ZnO Nano-Agglomerates as a Potential Scaffold for Non-Enzymatic Hydrogen Peroxide Sensing

Co-doped ZnO nano-agglomerates were synthesized by a facile solution process. Several characterization techniques revealed the successful doping of the ZnO by Co ions. FESEM results showed the agglomeration of the Co-doped ZnO nanoparticles to form large-sized nano-agglomerates. The diameters of the spherical nanoparticles and the agglomerates were not found to be uniform. The diameters of the nano-agglomerates ranged from ~25 nm–120 nm. XRD spectrum confirmed the Wurtzite hexagonal phase of ZnO in Co-doped ZnO nanoagglomerates. The average particle size for Co-doped ZnO nano-agglomerates was 20.68 nm. The sensing parameters were examined by using Co-doped ZnO nano-agglomerates modified gold electrode through cyclic voltammetric and amperometric analysis. The sensitivity of 70.73 μAmM−1cm−2 and very low-detection limit of 0.2 μM was observed for H2O2. The corresponding linear dynamic concentration range was 0.2–1633 μM. The excellent sensing activities of the Co-doped ZnO nano-agglomerates for H2O2 were attributed to the improved intrinsic electric properties and increased inner defects density, particularly near the interface region.

Low temperature induced red-shift in violet-blue emission from Zn(Al, Ag)O nanoparticles

ABSTRACT To the best of our knowledge, we present the first study on temperature-dependent photoluminescence (PL) of Al-doped and Ag co-doped ZnO nanoparticles (NPs) obtained by sol-gel co-precipitation. FTIR spectra revealed the presence of Zn-O, Al-O and Ag-O bonds in the respective samples. FESEM images showed spherical NPs in undoped ZnO, which were transformed into granular and rod-like structure by Al doping and subsequently Ag co-doping developed flower-like structure having pin pointed nanorods embedded in petals. Red-shift of the band-gap of ZnO was noticed which is attributed to the contribution of charge carriers by Al and Ag. The PL emission peaks got red-shifted on incorporating with Al and Ag because of the creation of extended energy level network. Reduction from room temperature to −10°C also led to a red-shift of PL emission peaks. This combined impact of doping, co-doping and temperature opens-up a new avenue of designing materials for luminescence thermometry.

Optimizing physical properties of Co-doped ZnO nanoparticles: Controlling oxygen vacancy and carrier concentration

The origination of magnetism in Co-doped ZnO-based dilute magnetic semiconductor (DMS) with room temperature ferromagnetism (RTFM) has some controversy. In this paper, Zn1-xCoxO nanoparticles (x = 0.00, 0.01, 0.03 and 0.05) were prepared using sol-gel method. The relationship between oxygen vacancy or carrier concentration and magnetic properties were investigated. The hexagonal wurtzite structure of all the samples was confirmed by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The morphological features were investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM), and the optical properties, including energy gap, were analyzed by ultraviolet–visible spectroscopy (UV–vis). The number of oxygen vacancies (VO) was measured by X-ray photoelectron spectroscopy (XPS), which is positively correlated with the Co content. The RTFM properties were analyzed by physical properties measurement system (PPMS). The results reveal that a higher carrier concentration is critical to promoting ferromagnetism. And, the magnetism of Co-doped ZnO may originate from VO defects or the carrier.

Synthesis and Optical Properties of B-Mg co-Doped ZnO Nanoparticles

Doping impurity into ZnO is an effective and powerful technique to tailor structures and enhance its optical properties. In this work, Zn1−xMgxO and Zn1−x−yMgxByO nanoparticles (x = 0, 0.1, 0.2, 0.3, 0.4; y = 0, 0.02, 0.04) were synthesized via one-pot method. It shows that the Mg and B dopants has great influence on crystallinity and surface morphology of ZnO nanoparticles, without changing the wurtzite structure of ZnO. The band structure study indicates that the competition of Conductive Band (CB) shift, Burstein–Moss (B-M) shift and Shrinkage effect will cause the band gap energy change in ZnO.

Enhancing structural and optical properties of ZnO nanoparticles induced by the double co-doping of iron and cobalt

The (Fe,Co) codoped ZnO nanoparticles were synthesized through PEG assisted route and characterized by XRD,UV visible and SEM with EDAX analysis. The structural analysis shows that the synthesized nanoparticles have crystalline nature and the crystallite size is found to be 49.43 nm. The UV visible spectrum shows that the energy band gap of synthesized nanoparticles was found to be 2.9 eV. The structural morphology was found by SEM analysis and the synthesized sample forms a cluster structure. The presence of Fe, Co and ZnO were confirmed by EDAX analysis. This promotes its utilization in optoelectronic devices.

The effect of annealing time and gas flow rate on optical and magnetic properties of (Al,Co) co-doped ZnO nanoparticles by varying Al concentration

The effect of Al, a trivalent substitution was investigated in Co doped ZnO with regards to the role of additional carriers in n-type magnetic semiconductors. Nanoparticle samples of Zn1?xCo0.04AlxO with different Al compositions (x = 0, 0.005, 0.010, 0.015 and 0.020) were annealed at 600 oC for different time (5 hours and 8 hours) and different gas flow rates (25 sccm and 50 sccm). All nanoparticles attained Wurtzite hexagonal structure in a stable form after annealing in forming gas. The effect of annealing time and gas pressure were investigated. Magnetization measurements revealed that air annealed samples displayed paramagnetic properties. Nevertheless, after annealing in forming gas, magnetic moments are stabilized and follow a monotonic trend. Diffuse reflectivity measurements revealed the incorporation of Co2+ ions into the Wurtzite hexagonal lattice. The optical band-gap was found to be increasing with increasing Al concentration of up to 0.01, followed by a decrease with further increase in Al concentration