Ni ZnO Research Articles

Optical properties analysis of gelatin-based prepared Co, Ni, and Mn-doped ZnO nanoparticles in infrared and UV–vis region using Kramers-Kronig methods

This study investigates the structural, optical, and morphological properties of ZnO nanoparticles doped with Ni, Mn, and Co (Zn0.97A0.03O where A = Ni, Mn, and Co, designated as ZN, ZM, and ZC, respectively). X-ray diffraction (XRD) analysis confirms the successful incorporation of dopants into the ZnO lattice without altering its wurtzite structure. Field emission scanning electron microscopy (FESEM) images reveal that doping results in larger and more uniformly distributed particles. Energy-dispersive X-ray spectroscopy (EDX) verifies the presence of Ni, Mn, and Co in the respective samples. Fourier transform infrared (FTIR) spectroscopy indicates an increase in average phonon energies due to doping, as evidenced by the shift in the Zn-O vibration peak. Ultraviolet–visible (UV–vis) spectroscopy shows that doping causes a blue shift in the absorbance peak and increases the optical band gap from 3.17 eV for pure ZnO to 3.22 eV for Co-doped ZnO. Transmission electron microscopy (TEM) and corresponding EDX results further confirm the presence of dopants and illustrate that doped ZnO nanoparticles are larger than pure ZnO particles. These findings provide valuable insights into the impact of doping on ZnO nanoparticles, potentially enhancing their suitability for various technological applications.

CaAl1.5Fe0.5O4/6%Ni-ZnO nanocomposites: Synthesis, characterization and effective photocatalyst for the photocatalytic degradation of methylene blue dye

This study focuses on synthesizing and analyzing properties of calcium aluminate photocatalytic nanoparticles using the microwave (MW) combustion method by following the rules of green chemistry and investigates their effectiveness in the adsorption of methylene blue (MB) dye which is a crucial contaminant that enters water resources. The synthesized nanoparticles, including CaAl2O4 (CAO), CaAl1.5Fe0.5O4 (CAFO), 6 %Ni-ZnO (NZO), and CaAl1.5Fe0.5O4/6%Ni-ZnO (CAFONZO) composites, were characterized using various techniques. XRD analysis confirmed the formation of spinel structures in all samples. The crystallite size and lattice constants were determined, showing a reduction in Crystallite size of CAO from 45.98 nm to 37.55 nm after Fe3 + doping. Then, with the formation of CAFONZO Crystallite size 13.99 nm was obtained. FT-IR analysis revealed the chemical interactions between atoms in the spinel structures Nitrogen adsorption/desorption isotherms were used to determine the specific surface area of nanoparticles, pore volume, and pore size. Specific surface area of CAO, CAFO, and CAFONZO are 1.637, 1.745, and 9.903 (m2/g), respectively. SEM and TEM images provided insight into the morphology and size of the nanoparticles. According to TEM images, after Fe3 + doping, the size of particles decreased from 85 to 32 nm. UV-DRS was performed to determine the optical band gap energy of the photocatalysts. The calculated band gap values of pure CAO, CAFO, and NZO nanoparticles were 3.2 eV, 2.5 eV, and 2.7 eV, respectively. Mott-Schottky analysis indicated the type of semiconductors and the energy levels of the conduction and valence bands. Valence band (VB) values of CAFO and NZO are 2.86 eV and 2.03 eV, respectively. The photocatalytic activity of the nanoparticles was evaluated by degrading MB under visible light illumination. The adsorption studies were conducted by varying the dosage, pollutant concentration, and pH. The results showed that CAFONZO nanoparticles exhibited the highest photocatalytic efficiency, achieving 96 % degradation of MB within 120 min. The combined photocatalyst demonstrated improved efficiency compared to the individual components.

Investigating the dielectric and ferromagnetic behaviour of Ni and Co dual doped ZnO for diluted magnetic semiconductor

Herein, Ni/Co co-doped ZnO nanoparticles (NPs) were successfully prepared via chemical co-precipitation process. The structural, purity and crystallite size of as-prepared particles were confirmed by using x-ray diffraction (XRD). The results revealed the hexagonal wurtzite structure of ZnO without any impurity phase of as-prepared samples. The crystallite size decreased from 34.9 to 9.6 nm, whereas lattice strain reduced to 0.00086. The change in crystallite size, lattice parameters, strains and dislocation density further indicates the successful incorporation of dopants in ZnO host lattice. The dielectric properties, ac conductivity, and magnetic behaviour were steadily examined. The dielectric constant has been found to be 1070 with 5wt% at low frequency and become constant at higher frequency. It was revealed that dopant additions lead to attain high dielectric constant and low loss possibly attributed to interface polarization, and dipole polarization due to oxygen vacancy defects. M-H measurement observed that ferromagnetism at room temperature pure and doped ZnO samples. The ferromagnetic behaviour of pure ZnO NPs with Ms = 0.17 emu g−1, Mr = 0.11 emu g−1 and Hc = 67 which was increased to Ms = 0.85 emu g−1 and Mr = 0.65 emu/g for 5wt% Co. This improvement with increasing Co concentration indicates that oxygen defects may stabilize the ferromagnetic order. These interesting features encouraging to use this material for ultrahigh dielectric materials and spintronics.

OPTICAL PROPERTIES AND ANTIBACTERIAL ACTIVITY OF Ni, Mg, AND Fe-DOPED ZnO

In recent years, research on pure ZnO, Ni-doped ZnO, Mg-doped ZnO, and Fe-doped ZnO nanostructures has been gradually progressing to create more effective materials that may be applied in a variety of applications. In this investigation, hydrothermal synthesis was used to create both pure ZnO nanoparticles and ZnO that had been doped with Ni, Mg, and Fe at a concentration of 7%. Before testing the nanostructures’ ability to inhibit harmful bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterobacter sp.), they were shown to have antibacterial activity. With the use of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and ultraviolet–visible (UV–Vis), their physicochemical characteristics were initially determined. When Ni, Mg, and Fe are inserted into ZnO, XRD measurements show that the particle size decreases from 28.94[Formula: see text]nm to 19.96[Formula: see text]nm. The optical bandgap decreases from 3.17[Formula: see text]eV to 3.08[Formula: see text]eV with the least value for Fe/ZnO NPs, according to UV–Vis spectral data, which also shows that the absorption edge changes to higher wavelengths (redshift). This research has produced nanoparticle samples of Ni/ZnO, Mg/ZnO, and Fe/ZnO that, when compared to the pure ZnO sample, show intriguing antibacterial activity.

Band alignment studies of Zn1-xNixO/ZnO: As bilayer electron transport layer in perovskite solar cells

An efficient electron transport layer (ETL) is an essential requirement for performance and stability for perovskite solar cells. In this study, we have opted Zn1-xNixO/ZnO bilayer as is used electron transport layer instead of the ZnO single layer to overcome the trap-assisted recombination and also to enhance energy level alignment in the solar cell. For this, pristine ZnO and Ni-doped ZnO (Ni–ZnO) thin films were deposited on fused silica (Quartz) by pulsed laser deposition (PLD). For confirmation of the structural properties of deposited thin films, X-ray diffraction has been used. Electron affinity and band gap of these films have been evaluated by UPS and UV–Vis spectroscopy to design Zn1-xNixO/ZnO bilayer ETL. Further, planar perovskite solar cell has been schematized and simulated using SCAPS-1D software using experimentally designed bilayer ETL.

Improved photocatalytic activity for degradation of methylene blue dye using ZnO NPs

We present a plant-mediated green synthesized bare ZnO and Ni–ZnO NPs (nanoparticles) employing soursop leaf extract. The plant extract was treated with 0.1 M of Zn (NO3)2·6H2O The ZnO NPs have a wurtzite structure, according to XRD measurements. The mean size of the ZnO and Ni–ZnO NPs was examined to be 47.64 and 48.18 nm using an X-ray diffraction (XRD) pattern. The UV–visible spectrum displays absorbance maxima at 335 and 340 nm, which corresponds to an energy band gap of 3.28 and 3.24 eV for ZnO and Ni–ZnO NPs. Morphology studies show that the NPs are very permeable. The PL spectra of NPs revealed extremely intriguing blue, green, and red emissions following excitation at 391, 491 and 545 nm for ZnO and Ni–ZnO NPs, respectively. When exposed to UV light, the NPs exhibit photocatalytic efficacy for the reduction of methylene blue (MB) dye.

Aerosol metal-organic framework-derived Ni–Zn–Al hybrid catalyst for efficient methane Bi-reforming

Bi-reforming of methane (BRM) has emerged as a promising advancement in hydrogen production via direct carbon utilization. To promote BRM, metal-organic framework (MOF)-derived Ni–ZnO–Al2O3 hybrid catalyst was developed via aerosol-assisted approach. The results demonstrated that the incorporation of Al2O3 nanoparticle cluster and ZnO with Ni alloy enhanced the catalytic activity. Superior conversions of reactants and operation stability of the MOF-derived Ni–ZnO–Al2O3 hybrid catalyst was observed, and a high turnover frequency (TOFCH4) of 2.86 s−1 at a moderate operating temperature (650 °C) was achieved. Further, the H2/CO ratio of 1.4–6.5 was attained through the proper adjustment of feed ratios (H2O/CH4, CO2/CH4) and reaction temperature (600–700 °C). Overall, the newly fabricated MOF-derived Ni–ZnO–Al2O3 hybrid catalyst via aerosol-assisted method, demonstrated significant improvements in reducing the required operating temperature of BRM, which is beneficial for simultaneous reduction of the CO2 generated from the methane reforming plus energy consumption, and advancing the development of low-carbon H2 production.

Study of structural, optical and electrical properties of Nickel doped ZnO (Ni–ZnO) nanorods grown by chemical bath deposition

To investigate the effect of Nickel on ZnO thin films, doped ZnO (Ni–ZnO) thin films were synthesized using chemical bath deposition on seed layers which were first grown using the conventional spray pyrolysis method. Structural, optical and electrical properties were studied at different doping levels of Ni (0, 2, 4, 6, 8 %). All samples exhibited a highly defined (002) peak indicating a strong hexagonal crystal structure orientation. The samples showed a red shift at E2L and E2H Raman modes indicative of structural alterations. The undoped, 2 % and 4 % Ni doping levels showed lower mean roughness values compared to the 6 % and 8 % Ni doping. The Introduction of Ni into the ZnO structure appears to reduce the grain size from 167 nm to the lowest 79 nm at 2 % Ni concentration. Optical and electrical properties showed that the introduction of Ni as a dopant led to improved transmittance of up 70 % within the visible range and reduced resistivity from 3.590*10−3 (Ωcm) at undoped ZnO to 0.616*10−3 (Ωcm) 2 % Ni doped ZnO concentration.

Influence of doping with Co, Cu and Ni on the morphological and structural parameters and functional properties of ZnO nanoobjects

Recently, ZnO nanoobjects (nanoparticles, nanosheets, nanorods, nanoflowers, etc.) have been extensively studied due to their unique dielectric, optical and photocatalytic properties. Appearing on a nanoscale, these properties make ZnO nanoobjects a promising material in optoelectronics, photocatalytic degradation of cyclic pollutants in wastewater and other applications. Introducing 3d elements into the ZnO lattice not only results in appearing additional levels in the band gap, but also significantly impacts the process of nanoobject formation. While many works were devoted to the former issue, the latter has not been fully studied yet, which determined the direction of this work.In this context, we obtained undoped and Cu-, Co- and Ni-doped ZnO nanoobjects by the precipitation method. To study morphological and structural parameters of the samples obtained, they were characterised by a set of methods (XRD, SEM, FTIR, AES-ICP, SSA, XPS, Raman and absorbance spectroscopy). The developed approach was used in order to evaluate the amount of oxygen vacancies and defects in (un)doped ZnO from XPS and Raman spectra. As for functional properties, impedance spectroscopy as well as photoluminescence and photocatalytic activity studies were conducted.In this work, it was discovered that crystallite sizes become greater for doped ZnO nanoobjects and their values depend on the dopant hydroxo complex equilibrium constants. Doping changes a shape of nanoobjects: ZnO, Cu–ZnO and Ni–ZnO are nanosheets of different thickness, but Co–ZnO has a shape of nanoflowers. Oxygen vacancy and defect amount also changes in case of doped samples. As for functional properties, doping leads to an increase of photoluminescence, reduces ZnO nanoobjects’ dielectric losses and enhance photodegradation velocity of methylene blue.The results of the comprehensive study reveal the possibility of changing morphological, structural and consequently, functional parameters of ZnO nanoobjects by varying the chemical nature of the dopant. This leads to new opportunities in developing materials with desired properties.

Optimization of phosphorus-loaded Ni–ZnO crosslinked carboxy methyl cellulose-based biodegradable nanocomposite hydrogel beads for the slow release of P, Ni and Zn: a kinetic approach

Phosphorus-loaded Ni–ZnO crosslinked carboxy methyl cellulose-based biodegradable nanocomposite hydrogel beads as multinutrient source of slow release fertilizer.

Ni-Decorated ZnO Monolayer for Sensing CO and HCHO in Dry-Type Transformers: A First-Principles Theory

This work implements first-principles simulations in order to investigate the Ni-decorating property on the ZnO monolayer and the sensing property of the Ni-decorated ZnO (Ni–ZnO) monolayer upon CO and HCHO molecules formed in the dry-type transformers. The results reveal that the Ni dopant is stably anchored on the TO site of the ZnO surface forming the Ni–Zn and Ni–O bonds with the binding energy (Eb) of −1.75 eV. Based on the adsorption energy (Ead) of −1.49 and −2.22 eV for CO and HCHO on the Ni–ZnO monolayer, we determined the chemisorption for two such systems. The band structure (BS) and atomic density of state (DOS) of the gas adsorbed systems are analyzed to comprehend the electronic property of the Ni–ZnO monolayer in the gas adsorptions. Besides, the change of bandgap and work function uncover the sensing potential of Ni–ZnO monolayer upon CO and HCHO detections, with admirable electrical response (15,394.9% and −84.6%). The findings in this work manifest the potential of Ni–ZnO monolayer for CO and HCHO sensing to evaluate the operation condition of the dry-type transformers.

Carbon nanofiber supported Ni–ZnO catalyst for efficient and selective hydrogenation of pyrolysis gasoline

The Ni–ZnO/C nanofibers could be used directly for the hydrogenation of the model feed of pyrolysis gasoline without any passivation and exhibited better activity, selectivity, and stability than commercial Ni/Al2O3 catalyst.

Wear behavior of alkaline pulsed electrodeposited nickel composite coatings reinforced by ZnO nanoparticles

Nickel-ZnO nanocomposite coatings were fabricated by pulse electrodeposition in an alkaline bath. The effect of different deposition parameters such as current density, duty cycle, and pulse frequency as well as the impact of addition of 10 g/l ZnO nanoparticles into the nickel matrix on the friction behavior of fabricated coatings were investigated. X-ray diffraction, atomic force microscopy, scanning electron microscopy, microhardness test, and pin-on-disk wear test were utilized to assess the coatings characteristics, mechanical behavior, and wear resistance and a thorough comparison was performed between the pure nickel coating and its reinforced composite counterpart, with respect to their surface morphology, surface topography, and wear resistance properties. Our results indicate that by ZnO incorporation into the coating, the number of nucleation sites for nickel crystals increases, the crystal growth is retarded, and a nanocomposite coating with smaller grains can be fabricated. The incorporation of ZnO led to significantly increase in microhardness, changed the wear mechanism from adhesion to abrasion, and improved the wear rate. By increasing the electrodeposition current density (from 4 to 10 A/dm2), the wear rate was noticeably decreased while the friction coefficient was significantly enhanced. As the electrodeposition duty cycle and pulse frequency were increased to 75% and 100 Hz, respectively, wear rate of the composite coating increased noticeably as a consequence of the changes in the coating properties. The optimum electrodeposition condition for Ni–ZnO nanocomposite coatings was achieved at 10 A/dm2, γ = 50% and f = 10 Hz resulting in a coating with the lowest wear rate (3.2539 × 10−4 mm3/Nm), minimum weight loss (0.0014 gr), highest microhardness (290 Hv), maximum ZnO incorporation rate (4.04 vol% ZnO), and highest friction coefficient (0.972) among all investigated coatings. It was concluded that increasing current density improved the wear resistance while the enhancement of duty cycle and pulse frequency led to worsen it.

Electrodeposition of Ni–ZnO nano-composite for protecting the agricultural mower steel knives

There is little information about the improvement of agricultural reciprocating mower knives against wear and corrosion using nanotechnology. Therefore, in the present study, the electrodeposition of pure Ni and Ni–ZnO nano-composite coatings has been used. The influence of pH values and the applied current density on the surface morphology, corrosion resistance, and mechanical properties as abrasion resistance, scratch, and fretting tests of Ni and Ni–ZnO nano-composite coatings using nanoindentation machine have been investigated. The results demonstrated that Ni deposited on steel from the alkaline bath displayed fine grain sizes than that deposited from the acidic bath. EDX analysis proved that the maximum incorporation of ZnO (2.7 wt%) into the Ni matrix was achieved with an alkaline bath at 5A/dm2. High-performance properties were obtained with the steel coated by Ni–ZnO nano-composite coating from an alkaline bath. The surface is harder (4.8 Gpa) than the steel coated by pure Ni (2.8 Gpa) and consequently exhibited a higher ratio of the hardness, the resistance to the plastic indentation, elastic recovery, scratching, fretting, abrasion, and corrosion resistance (in 3.5% NaCl solution). The highest corrosion resistance (0.0047 mm/year) compared with uncoated steel (0.094 mm/year) was obtained with the steel coated by Ni–ZnO nano-composite from the alkaline bath containing 1 g/L ZnO operated at 5 A/dm2 and pH 10. The testing results concluded that the steel coated by Ni–ZnO nano-composite coating from an alkaline bath appears promising to protect mower knives.

A novel strategy based on magnetic field assisted preparation of magnetic and photocatalytic membranes with improved performance

Membrane fouling problem is the bottleneck for commercial applications of separation membranes. The current study offered a first report on preparation and performance of the magnetic and photocatalytic poly (vinylidene fluoride) (PVDF)-Ni-ZnO composite membranes for the antifouling purpose. Magnetic Ni–ZnO particles (NZPs) was firstly prepared via an in-situ reduction reaction. Thereafter, the NZPs were attracted onto a PVDF membrane surface through a magnetic force effect. The PVDF-NZPs composite membrane displayed magnetic property, photocatalytic property and obviously higher antifouling performance than that of bare PVDF membrane. Particularly, the flux recovery rates (FRR) of the optimal PVDF-NZPs membrane reached to 100%, 100%, 83% and 83% for filtration of humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA) and yeast solutions, respectively, which are comparable or much better than most of the literature data. In addition, it was found that acid-based (AB) interaction of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) results played the predominant role during the fouling process. The ultrahigh FRR of the modified PVDF-NZPs membrane mainly stemmed from its in-situ and persistent photocatalytic activities. The current work not only offered a novel membrane modification method, but also presented the modified membranes with enhanced performance for water treatment.

Photodegradation of methylene blue dye by powders of Ni–ZnO floweret consisting of petals of ZnO nanorod around Ni-rich core

The photocatalytic effect of the powder particles resembling a flower consisting of Ni and nanorods of ZnO was studied for the degradation of methylene blue (MB) dye, an organic pollutant in water. Mechanical alloying of pure Ni and Zn powders followed by dealloying in high pH electrolyte was used for the synthesis of the photocatalyst. The effect of catalyst dose, concentration (ppm) of the MB and pH of the solution on the performance of catalyst and kinetics of photodegradation were analysed. The as-prepared catalyst was found to be re-useable multiple times without any secondary post treatment to the catalyst.

Ni–ZnO nanocomposites assembled under various morphologies like columnar, nanochains, and granular structure for removal of pollutants

A unique three dimensional (3D) porous Ni–ZnO heterojunction nanocomposites were synthesized by a simple sonochemical approach followed by annealing the zinc and nickel oxalate composite precursor formed at 400–600 °C. Simple calcination leads to generate novel 3D porous nanostructures such as columnar, nanochain, and granular structure with a high surface area. Also, the prepared morphological Ni–ZnO nanostructure provides an efficient photocatalytic improvement under visible light range. The columnar-like morphology Ni–ZnO photocatalyst degrades 100% of methylene blue (MB) in 270 min while the methyl orange (MO) in 360 min under visible light irradiation. Ni–ZnO nanocomposites calcined at 400 °C shows relatively high adsorption capacities for MB and MO due to good electrostatic interaction between Ni–ZnO and dyes. Whereas Ni–ZnO nanocomposites calcined at 500 °C and 600 °C have fewer adsorption capacities for MB and MO due to aggregation of particles.

ELECTRICAL CONDUCTIVITY STUDIES OF ZINC OXIDE, NICKEL DOPED ZINC OXIDE POLY(O-TOLUIDINE) NANOCOMPOSITE USING CHEMICAL OXIDATIVE POLYMERIZATION

Nanocomposite semiconductor material comprising Zinc oxide (ZnO), Nickel doped Zinc oxide and Poly(o-toluidine) polymeric composites were synthesized in two stage synthesis process. Solgel technique is adopted in the material synthesis of semiconductor particles of ZnO and Ni/ZnO (NZO), as well a proven technique of chemical oxidation of o-toluidine is attempted to prepare the semiconductor polymeric composites (ZPOT, NZPOT) and pure POT. The synthesized polymeric composites were characterized by (UV-Visible, XRD, SEM, FT-IR and TGA) spectroscopic studies. The addition of semiconductor material into the o-toluidine polymer resulted in a crystalline shape was confirmed from SEM image. Incorporation of metal oxide into polymeric composites showed a significant difference in the conductivity properties which were observed from DC conductivity studies.

Microstructural and optical properties of Ni-doped ZnO thin films prepared by chemical spray pyrolysis technique

In this study, multifunctional ZnO and Ni-doped ZnO thin films were prepared by chemical spray pyrolysis technique (SPT) on soda lime glass substrates at 300 °C. The liquid precursors for the films were synthesized from high purity zinc acetate (Zn (CH3COO)2.2H2O) and nickel acetate (Ni (CH3COO)2.3H2O). In order to vary the concentrations of the metallic constituents in the films, the precursors were prepared at 0.1 M, 0.15 M, 0.2 M and 0.25 M in distilled water. For the Ni-doped ZnO thin films, the mixing ratio of the precursor was in proportion of nickel acetate 0% to 10% by volume of the zinc acetate. Meanwhile, deposition parameters i.e. temperature, substrate distance and deposition time were optimized to achieve good quality thin films. Rutherford Backscattering spectroscopy (RBS) result shows an increase in oxygen content in ZnO film with 84% compared to Ni–ZnO thin films. The thickness of ZnO was observed to be lower than Ni–ZnO thin films, however a marginal increase in the thickness of Ni–ZnO thin film was observed with increase in Ni2+ content. Visual observation and spectrophotometer results indicated that the films are highly transparent in the UV-visible region. Ni–ZnO films were observed to have a higher transmittance than ZnO thin films, with increase in transmittance with Ni2+concentrations. The absorption edge of ZnO was observed to be lower than Ni–ZnO, and the optical band gap of undoped ZnO thin film decreased slightly from 3.28 eV to 3.20 eV of 10% Ni-doped ZnO thin film.

Comparison of the adsorption of H2S by ZnO–TiO2 and Ni–ZnO–TiO2 nanoparticles: An adsorption isotherm and thermodynamic study

AbstractNanoparticles were synthesized by the sol–gel method and evaluated for adsorption of hydrogen sulfide using a continuous fixed‐bed column. The effects of the parameters were examined, and the optimum values for nanoparticles were found to be mass of adsorbent 0.2 g, gas volume 5.7 L, flow rate 0.22 L min−1, and gas pressure 7 Psi at 12 °C. These conditions resulted in a maximum adsorption of H2S of 83.24% and 90.43% for ZnO–TiO2 and Ni–ZnO–TiO2 nanoparticles, respectively. The equilibrium data were best represented by the Freundlich isotherm. The thermodynamic parameters indicated that the adsorption was spontaneous and exothermic in nature.