Co-doped ZnO Nanoparticles Research Articles

Aloe vera assisted green synthesis of Ag and Cu co-doped ZnO nanoparticles and a comprehensive analysis of their structural, morphological, optical, electrical and antibacterial properties

This study investigates the potential of utilizing Aloe vera-assisted green synthesis with transition metal dopants of Ag and Cu for greater efficiency and sustainability in advanced scientific applications utilizing ZnO nanoparticles. Samples were prepared using the co-precipitation method, maintaining a basic pH media of 10. Aloe vera gel extract was chosen for its acclaimed role as a stabilizing and reducing agent and its proven antioxidant, antibacterial, and anticancer properties. The XRD report revealed the hexagonal Wurtzite crystal structure of nanoparticles, exhibiting a crystallite size range of 17–23 nm with substantial alterations in lattice parameters, dislocation density, and bond lengths when dopants were added. Additionally, EDX analysis confirmed the perfect doping of Ag and Cu in ZnO without any impurities. SEM analysis indicated a reduction in agglomeration, accompanied by a transition in particle morphology from columnar to globular. Additionally, the optical study showed a band gap range of 3.18–3.27 eV, confirming it to be a wide band gap semiconductor. The effect of dopants resulted in an increase in transparency and band gap, while a decrease in absorption coefficient in the visible wavelength region. With increasing temperature, a decline in electrical resistivity was noted, with co-doped nanoparticles consistently exhibiting the lowest resistivity, affirming semiconductor characteristics. Most importantly, A remarkable antibacterial efficacy was noticed at low concentrations against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The zone of inhibition produced by nanoparticles exhibited values akin to the antibiotic control, even at substantially lower doses. This research offers a comprehensive analysis of the effects of Ag and Cu in Aloe vera-assisted green-synthesized ZnO nanoparticles, concurrently addressing their potential applications in biomedical, energy storage, and optoelectronic devices.

Synthesis and characterization of cobalt doped zinc oxide nanoparticles and their application for catalytic reduction of methylene blue dye

The co-precipitation approach has been used in the current research work to synthesize cobalt-doped zinc oxide nanoparticles (ZnO NPs) employing zinc and cobalt nitrate hexahydrate as precursor salts. Ultraviolet-visible spectra and Fourier transform infrared were used to confirm that the manufacturing procedure was efficient and that the synthesized sample contained a range of unique binding sites. The catalytic efficacy of the prepared nanoparticles for the reduction of Methylene blue dye in the presence of NaBH4 as a reducing agent has been investigated. The concentration of methylene blue, the catalyst dose, and the concentration of sodium borohydride all play significant roles in the catalytic reduction of methylene blue (MB). The best result for the complete reduction of methylene blue was obtained in 14 min of reaction time. Catalytic reduction of methylene blue in the involvement of synthesized nanoparticles was found to be followed by the Langmuir-Hinshelwood mechanism. Concerning this process, the reduction reaction is affected by the quantity of methylene blue, catalyst, and sodium borohydride. This effective catalytic activity of Co-doped ZnO nanoparticles suggests that these NPs can work wonders as nano-catalysts for the reduction of hazardous dyes.

Exploring the synergistic influence of Cu and Co co-doping on the optical properties of ZnO nanoparticles

In this study, we synthesized Cu and Co co-doped ZnO nanoparticles, denoted as Zn1-2xCuxCoxO (x = 0.01, 0.02, 0.03), using the sol-gel auto-combustion method. Successful integration of Cu and Co elements into the ZnO host lattice was confirmed through a comprehensive array of spectroscopic techniques. Structural analysis revealed the persistence of a hexagonal wurtzite crystal structure with some distinct microstructural variations across all samples. Alteration in lattice parameters and dislocation density strongly suggests the successful incorporation of Cu2+ and Co2+ ions within the ZnO lattice. A prominent increase in crystallite size from 27.19 nm to 33.46 nm was observed with the increase in doping concentration. Field emission scanning electron microscopy showed a combination of uniformly distributed spherical and hexagon-like structures. Furthermore, UV–Visible absorption spectra demonstrated a proportional enhancement in energy band gap from 2.14 eV for Zn0.98Cu0.01Co0.01O to 2.40 eV for Zn0.94Cu0.03Co0.03O. The Burstein−Moss effect was invoked to elucidate the observed blue shift in absorption spectra and energy band gaps, further solidifying our findings. The systematic and substantial correlation between dopant concentration and energy band gap signifies that the co-doping of Cu and Co is a viable strategy for engineering the band gap of ZnO. This collective investigation unveils the substantial potential of Cu and Co co-doping in ZnO nanoparticles for advanced optoelectronic applications, paving the way for tailored optical and photonic functionalities.

Combustion synthesis and characterization of visible-light-driven La/Al co-doped ZnO nanoparticles used for wastewater treatment

Visible-light-driven LaxAl0.03-xZn0.97O (x = 0.01, 0.015 and 0.02) nanoparticles were synthesized by tartaric acid-assisted combustion method. Both ZnO and La/Al co-doped ZnO samples were indexed to the pure hexagonal wurtzite ZnO structure and were composed of nanoparticles with particle size ranges of 100-150 nm and 20-50 nm, respectively. The photocatalytic activities of ZnO and LaxAl0.03-xZn0.97O (x = 0.01, 0.015 and 0.02) nanoparticles were monitored through the degradation of methylene blue (MB) under visible light irradiation. The La0.02Al0.01Zn0.97O nanoparticles have the highest photocatalytic activity in degrading of MB under visible light irradiation because the La/Al co-dopant played the role in creating shallow energy level under the conduction band of ZnO.

Correlations between structural, dielectric properties, and ab initio calculations in Co-doped ZnO nanoparticles: effect of Co concentration

Correlations between structural, dielectric properties, and ab initio calculations in Co-doped ZnO nanoparticles: effect of Co concentration

Investigation on the Effect of Cu and Mg Concentration on the Optical and Structural Properties of Doped and Co-doped ZnO Nanoparticles

Investigation on the Effect of Cu and Mg Concentration on the Optical and Structural Properties of Doped and Co-doped ZnO Nanoparticles

Enhancing the optical, electrical, dielectric properties and antimicrobial activity of chitosan/gelatin incorporated with Co-doped ZnO nanoparticles: Nanocomposites for use in energy storage and food packaging

The solution casting method was utilized to produce a brand of new nanocomposites made of chitosan (Cs), gelatin (Ge), and co-doped ZnO nanoparticles (NPs). The physicochemical characteristics of these nanocomposites were examined using a variety of methods. The doped samples' XRD patterns clearly demonstrated changes in the structural features of the Cs/Ge host polymer, with the widening of the peak at 2θ = 20.31 becoming more prominent as Co-doped ZnO NPs concentration increased. Tauc's relation was utilized to describe the direct and indirect bandgap energies using UV–Vis analysis. By including 3.5 wt% of Co-doped ZnO NPs, the optical energy gap direct and indirect of pure Cs/Ge was reduced from 5.22 to 4.92 eV to 4.90 and 4.42 eV, respectively. Co-doped ZnO NPs reinforcing has a significant impact on the in ac conductivity, dielectric constant and loss tangent values. An ionic conductivity of 1.089 × 10−7 S/cm at Cs/Ge-3.5 wt% Co-doped ZnO NPs was observed. The nanocomposites' antimicrobial effect on bacteria and fungi was tested. The adding of 3.5 %Co-doped ZnO NPs improved the activity against S. aureus (22 mm), E. coli (13 mm), A. niger (29 mm), and C. albicans (27 mm) despite the fact that the investigated pure mix had no effect on the microbiological strains. The current research's remarkable findings in terms of optical, dielectric, electrical, and antimicrobial effects indicate that Cs/Ge-coated ZnO film will have significant uses in both food packaging and energy storage devices.

Estimation of microstructural parameters by Williamson–Hall, Halder–Wagner, and size–strain plot methods and magnetic properties of (Cu/Mn) co-doped ZnO nanoparticles

Estimation of microstructural parameters by Williamson–Hall, Halder–Wagner, and size–strain plot methods and magnetic properties of (Cu/Mn) co-doped ZnO nanoparticles

Synergistic enhancement of photocatalytic and antimicrobial efficacy of nitrogen and erbium co-doped ZnO nanoparticles

Using the chemical co-precipitation approach, a series of nitrogen (N) and erbium (Er) co-doped ZnO nanoparticles (NPs) was effectively synthesized to enhance the photocatalytic and antibacterial activities. Several characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis, and photoluminescence (PL) spectroscopy, were carried out to validate the evaluated photocatalytic and antibacterial activities. XRD analysis confirms the pure wurtzite ZnO phase without the presence of any secondary phase. XPS analysis confirms the successful incorporation of nitrogen and erbium into the ZnO matrix. The optical bandgap of ZnO calculated from UV-vis spectroscopy shows a redshift after Er–N co-doping, with the lowest bandgap of 3.215 eV calculated for Zn0.97Er0.03N0.01O0.99 NPs. SEM images demonstrate the formation of nanorods after N–Er co-doping, followed by gradually increased rod diameter and length after N–Er co-doping. Moreover, the photocatalytic activities of ZnO samples were measured by their ability to facilitate the photodegradation of Rhodamine B under UV irradiation. ZnO with 1 mol% N doping exhibits 88% photodegradation of RhB under UV light within 360 min, and the photodegradation and antibacterial activity are greatly improved with Er co-doping. In fact, 3 mol% Er-1 mol% N doped ZnO NPs demonstrate the highest photocatalytic activity, with approximately 96% degradation after 360 min, as well as superior antibacterial activity against Staphylococcus aureus (Gram-positive bacteria) and Pseudomonas aeruginosa (Gram-negative bacteria) with the highest zone of inhibition (ZOI) of 16 nm, due to nanorod formation, increased reactive oxygen species (ROS), and decreased electron–hole recombination, as validated by SEM, XPS, and PL spectroscopy.

Structural, optical and photocatalytic properties under UV-A and visible lights of Co–, Ni- and Cu-doped ZnO nanomaterials. Comparative study

In this investigation, Co–, Ni- and Cu-doped ZnO nanoparticles were prepared using precipitation methods. The characterization of the as-prepared nanomaterials was carried out using XRD, FT-IR, DRS, XPS and SEM. The XRD analysis showed that the insertion of foreign metal ions into the matrix of ZnO caused a slight shift of the positions of (100), (002) and (101) diffraction peaks of ZnO towards the lower 2θ, by comparison with pure ZnO. The DRS results showed that Co-doped ZnO nanoparticles absorb wavelengths higher than 400 nm. The estimated band gaps (eV) were 2.48, 3.17 and 3.14 for 10 %Co-ZnO, 10 %Ni-ZnO and 10 %Cu-ZnO respectively. The XPS results showed the existence of two valence states for Co and Ni (Co2+/Co3+ and Ni2+/Ni3+) while Cu exists in the form of Cu2+. The photocatalytic efficiency was evaluated under UV and visible irradiations in aqueous solution using methyl orange (MO) as an organic pollutant probe molecule. The results showed that, under visible light, the MO degradation increased significantly by doping ZnO (10 %Co-ZnO: 33.2 %; 10 %Ni-ZnO: 19.8 % and 10 %Cu-ZnO: 52.5 %) by comparison with undoped ZnO (9.3 %). The important increase in photocatalytic activity observed for the doped ZnO by comparison with pure ZnO, particularly for 10 %Cu-ZnO, has been linked to a synergistic effect of both the band gap narrowing and the increase in the lifetime of photogenerated charge carriers.

Silver and yttrium co-doped ZnO nanoparticles as a potential water splitting photocatalyst for the H2 evolution reaction

Silver and yttrium co-doped ZnO nanoparticles as a potential water splitting photocatalyst for the H2 evolution reaction

Significant impact of co-doping Eu-doped ZnO nanoparticles with Li on structural–optical properties relationship

ABSTRACT We describe here the structural evolution and optical properties of co-doping of Eu-doped ZnO nanoparticles with lithium synthesized by the sol-gel process. The characterization was carried out via X-ray diffraction (XRD), Fourier transmission infrared (FTIR), UV-Vis spectroscopy, and photoluminescence (PL) techniques. XRD confirmed hexagonal wurtzite phase of ZnO nanoparticles with crystallite size in the range of 22–61 nm. The band gap calculated from UV-vis spectra was in the range of 3.30–3.26 eV for undoped and Li and Eu co-doped ZnO nanoparticles, respectively, while photoluminescence study indicated that Li in Eu-ZnO affected the PL emission intensity, which was attributed to defects present in the crystal lattice. The field emission scanning electron microscopy (FESEM) images revealed the diverse morphology containing, spherical, tri-, tetra-, penta- and hexagonal rod-like nanostructures.

The effect of (In, Cu) doping and co-doping on physical properties and organic pollutant photodegradation efficiency of ZnO nanoparticles for wastewater remediation

In the present work, undoped, (Cu, In) doped and co-doped ZnO nanoparticles are successfully prepared by co‐precipitation technique. The molar concentrations of dopant elements are 2% for both Cu and In doping, and 1%–1% for the Cu/In co-doping. Energy dispersive X-ray (EDX) analysis confirms the chemical composition of the prepared nanoparticles, and proves the effective introduction of dopant elements into the ZnO host lattice. The X-ray diffraction (XRD) analysis indicates the formation of single-phase hexagonal wurtzite structure for the all synthesized samples. The morphological investigation shows change of ZnO nanoparticles from nanotubes to spherical shape under the effect of doping and co-doping. The reflectance spectra show red shift of the absorption edge as a result of Cu doping and Cu/In co-doping effect. The PL spectra confirm emission bands in the visible rage related to the presence of defects, such as oxygen vacancies, as well as shallow trap levels near the conduction band edge. These oxygen deficiencies have an important effect on the charge carrier transport, resulting in the enhancement of electrical conductivity in doped and co-doped ZnO. In addition, photocatalytic performance experiments prove that the photocatalytic activity of ZnO, in the degradation of amido black 10B dye, is significantly enhanced via (Cu, In) doping and co-doping.

Magnetic anisotropy in the ferromagnetic Mn and N doped ZnO Nanocrystals

(Mn, N)- codoped ZnO thin films were prepared by two step process. Study of Magnetic anisotropy in Mn and N codoped ZnO nanoparticles was studied. X-ray diffraction (XRD) &X-ray photoelectron spectroscopy (XPS) reveals that Manganese (Mn) and Nitrogen (N) ions in ZnO lattice exists as Mn2+ and N3-. Hysteresis measurement shows that at room temperature the samples show ferromagnetic nature and also indicate that the samples are having magnetic anisotropic behavior. This ferromagnetic nature in the samples is because of the hybridization between 2p of N & 3d of Mn state. The compound formed, corresponds to Mn-N-Mn cluster, which is found to be energetically strong enough for ferromagnetism at room temp.

Suppression of Visible Emission in Low-Temperature Synthesized Cobalt-Doped ZnO Nanoparticles and Their Photosensing Applications.

Cobalt (Co)-doped ZnO nanoparticles have been synthesized at 100 °C using a simple chemical technique, without post-deposition annealing. These nanoparticles are of excellent crystallinity and show a significant reduction in defect density upon Co-doping. By varying the Co solution concentration, it is observed that oxygen-vacancy-related defects are suppressed at lower Co-doping, while the defect density shows an increasing trend at higher doping densities. This suggests that mild doping can significantly suppress the defects in ZnO for electronic and optoelectronic applications. The effect of Co-doping is studied using X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), electrical conductivity, and Mott-Schottky plots. Photodetectors fabricated using pure and Co-doped ZnO nanoparticles show a noticeable reduction in the response time upon Co-doping, which again affirms the reduction in the defect density after Co-doping.

Structural, morphological, and optical properties of praseodymium and aluminium codoped ZnO nanoparticles

Using a soft chemical process that involves nitrates and heat annealing, nanoparticles of undoped ZnO and praseodymium, aluminum-codoped ZnO may be produced. XRD, SEM with EDS, and FTIR analysis determine nanocatalyst structures, morphologies, and chemical bonding. PL and UV spectroscopy examines optical characteristics. The peak in the FTIR spectral line at 714 cm-1 in the study indicates M-O stretching in the samples and ZnO's interaction with the Pr and Al matrix. XRD patterns indicated prepared nanoparticles with nanosizes ranging from 40.07 to 38.65 to 36.84 to 38.87 to 39.91 nm. SEM analyzed nanoparticle size, shape, and interaction with the Pr and Al matrix. EDS determined NPs purity. UV-vis spectra of ZnO-Pr/Al nanocomposites showed UV absorption similar to ZnO nanoparticles. Doping ZnO with Pr and Al shrinks the bandgap and slows photogenerated electron-hole pair recombination without changing its crystalline structure.

Hydrothermal-assisted synthesis of Co-doped ZnO nanoparticles catalyst for sodium borohydride dehydrogenation and photodegradation of organic pollutants in water

In recent years, studies on dye removal and hydrogen energy have gained momentum. However, these studies are still not in the desired position. Existing biological and physical methods for dye removal are quite inadequate. In hydrogen production, the efficiency is very low when a catalyst is not used. It is important to obtain inexpensive catalysts for both purposes. For this purpose, Cobalt doped Zinc oxide nanoparticles (Co-doped ZnO NPs) were synthesized using a one-pot flash combustion approach. The photocatalytic activity and hydrolysis process of the produced catalyst on NaBH4 were evaluated. The photocatalytic activity of Co-doped ZnO NPs was investigated for decolorization against certain dyes under sunlight irradiation. Co-doped ZnO NPs were analyzed for hydrogen production from NaBH4 hydrolysis. It has been determined that the nanomaterial has a superior catalytic activity with Turnover frequency (TOF) of 1682.3 min−1, 32.45 kJ/mol enthalpy (∆E),-158.4 J/mol.K entropy (∆S), and 34.94 kJ/mol activation energy (EA) obtained as a result of the hydrolysis reaction of Co-doped ZnO NPs. Their reusability was found to be 72.5% at the 4th cycle. The photocatalytic activity of the Co-doped ZnO NPs was found 81.22% (120 min) and 86.98% (90 min) against RhB and MB dyes, respectively. According to the results obtained, it has been seen that Co-doped ZnO NPs are reusable catalysts with high catalytic activity for hydrogen production as a clean energy source. At the same time, it was emphasized that a photocatalyst with high catalytic activity was obtained for wastewater treatment.

Structural, optical, photoluminescence and magnetic investigation of doped and Co-doped ZnO nanoparticles

We report here the structural, optical, photoluminescence (PL), and magnetic investigation of Zn1−x−yFexMyO nanoparticles. The lattice constants and crystallite size are decreased by Fe, followed by a further decrease up to (Fe + M) = 0.30. A compressive stress is approved and the size of particle is between 180 and 277 nm and follows the sample order of ZnO, (Fe + Cu), (Fe + Ni), and Fe. Although a single value of energy gap (Eg) is found for pure and Fe-doped ZnO, two values of Eg (Egh and Egl) are found for the co-doped samples. The Eg is generally increased by Fe, followed by a further increase for the Cu-series, whereas it is decreased for the Ni-series. The refractive indices nK and nT proposed by different methods are generally decreased by Fe, followed by a further decrease for both series. Although Fe doped ZnO depressed the density of carriers (N/m*), it increased again for the co-doped samples. The residual dielectric constant ϵL is decreased by Fe, followed by an increase for the Cu-series, but it is decreased for the Ni-series. The loss factor tan δ increases slightly with Fe, followed by an increase for the Ni-series, but it decreases in the Cu-series. A significant depression of optical conductivity σopt by Fe was obtained, followed by a further decrease which is higher for the Cu-series. The PL shows four visible emissions. Interestingly, an IR emission at about 825 nm is only obtained for the co-doped samples. Furthermore, the blue emission (Iblue) was higher than UV (IUV), [(Iblue/IUV) > 1], but it is greater for the Ni series than the Cu. Although ZnO exhibits diamagnetic behavior, the Fe and co-doped samples exhibit ferromagnetic with higher magnetization for the Ni-series than the Cu. The current results recommend the co-doped samples in nanoscale for some of advanced devices.

Preparation and Properties of (Cu, Ni) Co-Doped ZnO Nanoparticle-Reinforced Cu-Ni Nanocomposite Coatings.

Here, 2% Cu + 2% Ni co-doped ZnO nanoparticles were synthesized using the hydrothermal method and were used as particle reinforcements of Cu-Ni nanocomposite coatings prepared by electroplating technology. The effects of the added (Cu, Ni) co-doped ZnO nanoparticles (2-8 g/L) on the phase structure, surface morphology, thickness, microhardness, corrosion resistance, and photocatalytic properties of the coatings were investigated. The nanocomposite coatings have obvious diffraction peaks on the crystal planes of (111), (200), and (220), showing a wurtzite structure. The surface of the nanocomposite coatings is cauliflower-like, and becomes smoother and denser with the increase in the addition of nanoparticles. The grain size, thickness, microhardness, corrosion resistance, and photocatalytic properties of the nanocomposite coating reach a peak value when the added (Cu, Ni) co-doped ZnO nanoparticles are 6 g/L. At this concentration, the mean crystallite size of the coating reaches a minimum of 15.31 nm, and the deposition efficiency of the coating is the highest. The (Cu, Ni) co-doped ZnO nanoparticle reinforcement makes the microhardness reach up to 658 HV. The addition of nanoparticles significantly improves the corrosion resistance and photocatalytic properties of nanocomposite coatings. The minimum corrosion current density is 2.36 × 10-6 A/cm2, the maximum corrosion potential is -0.301 V, and the highest decolorization rate of Rhodamine B is 28.73% after UV irradiation for 5 h.

The role of defects in the structural and photocatalytic properties of Mg/B co-doped ZnO nanoparticles

The role of defects in the structural and photocatalytic properties of Mg/B co-doped ZnO nanoparticles