Zinc Aluminate Nanoparticles Research Articles

Effect of adding silver on photocatalytic properties of ZnAl2O4 nanopowder synthesized using microemulsion and polyacrylamide gel methods for recycled water

In recent decades, water purification and removal of organic pollutants such as organic dyes have been among the most important issues. Photocatalyst is one of the most effective methods for recycled water to eliminate organic pollutants and break them down into safe compounds. One of the most significant factors for determining the efficiency of photocatalyst nanoparticles is the utilization of new synthesis methods. Microemulsion and polyacrylamide gel methods are the two methods that were used for the synthesis of zinc aluminate nanoparticles for this study. The powders obtained from these two synthesis methods were characterized using the X-ray diffraction (XRD) technique, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and ultraviolet–visible spectroscopy (UV–Vis) which were utilized as photocatalysts in the photocatalytic degradation reaction of methylene blue (MB). The results demonstrated that the nanoparticles synthesized in both methods were of single-phase zinc aluminate with a spinel structure. The crystallite size obtained for zinc aluminate synthesized using the microemulsion method was 21.7 nm, whereas, in the polyacrylamide gel method, it was 26.3 nm. Microscopic images represented smaller and more uniform particle sizes in the nanoparticles obtained by the microemulsion method. The band gap energy of zinc aluminate nanoparticles obtained using microemulsion and polyacrylamide gel methods was 4.15 and 3.82 eV, respectively. Similarly, the results of MB removal showed that zinc aluminate nanoparticles synthesized using the microemulsion method and polyacrylamide gel, respectively, were 100% and 71% after 120 min. In the second phase of this study, silver nanoparticles were added to zinc aluminate nanoparticles during the synthesis process. X-ray diffraction showed that silver nanoparticles are formed metallically next to zinc aluminate. Moreover, the addition of silver decreased the crystallite size and slightly increased the band gap energy of zinc aluminate. The results of MB dye degradation tests in the presence of ZnAl2O4–Ag nanocomposites showed that the kinetics of dye degradation increased when the silver increased up to 5 wt%. Finally, the mechanism studied on dye degradation using scavenger agents showed that the main agents of dye degradation are the superoxide radical and the holes created in the valence band. It was consistently confirmed by examining the valence and conduction band potentials and also by comparing these potentials with those responsible for producing superoxide and hydroxyl radicals.

On the structural and optical characterization of zinc aluminate nanoparticles synthesized via green microwave route

Zinc aluminate, a widely employed wide bandgap semiconductor, boasts exceptional mechanical and thermal properties, coupled with a high quantum yield. Its versatile applications include photocatalytic pollutant degradation, utilization in displays, and contributions to the medicinal field. However, challenges arise during synthesis processes, where high-temperature annealing reduces nanoparticle surface area, and cation contamination from precursors impacts material purity. In response to these challenges, green synthesis methods incorporating plant extracts as reductants have emerged to yield higher-quality phosphors. In this study, the focus is on microwave synthesis of Zinc Aluminate using Zinc Nitrate and Aluminum Nitrate in varying ratios as precursors. Comprehensive structural and optical characterizations, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Diffuse Reflectance Spectroscopy (DRS), and Photoluminescence Spectroscopy (PL), have been conducted to assess the influence of precursor molar ratios on the spinel growth and optimization of the synthesis process.

Experimental Investigation of Calcium-Doped Zinc Aluminate Nanoparticles as a Promising Material for Microwave Applications.

Miniaturization of microstrip patch antennas (MPAs) is vital in applications such as wireless networks, mobile devices, global positioning satellites, and upcoming wireless terminals. This miniaturization has led to a demand for new materials with higher permittivity compared to the existing ones. Zinc aluminate (ZnAl2O4) ceramic is an exceptional and versatile material in this context, thanks to its high dielectric permittivity and low tangent loss, making it suitable for microwave applications. This article explores the feasibility of sol-gel-prepared Ca-doped ZnAl2O4 ceramic nanoparticles to be useful in fabricating a MPA. These nanoparticles were examined using X-ray diffraction, which confirmed their polycrystalline structure, and the morphological investigation evidenced the spherical grains having a mean diameter of 16 nm. The dielectric permittivity of the ZnAl2O4Ca nanoparticles is 21.11, with a tangential loss of 0.0247. A prototype MPA made by using Ca-doped ZnAl2O4 nanoparticles showed a return loss of -20.92 dB at a resonance frequency of 6.8 GHz with a bandwidth of 600 MHz. These results indicate that Ca-doped ZnAl2O4 ceramic nanoparticles possess exceptional dielectric characteristics, which make them a promising candidate for MPA applications.

Designed Y3+ Surface Segregation Increases Stability of Nanocrystalline Zinc Aluminate.

The thermal stability of zinc aluminate nanoparticles is critical for their use as catalyst supports. In this study, we experimentally show that doping with 0.5 mol % Y2O3 improves the stability of zinc aluminate nanoparticles. The dopant spontaneously segregates to the nanoparticle surfaces in a phenomenon correlated with excess energy reduction and the hindering of coarsening. Y3+ was selected based on atomistic simulations on a 4 nm zinc aluminate nanoparticle singularly doped with elements of different ionic radii: Sc3+, In3+, Y3+, and Nd3+. The segregation energies were generally proportional to ionic radii, with Y3+ showing the highest potential for surface segregation. Direct measurements of surface thermodynamics confirmed the decreasing trend in surface energy from 0.99 for undoped to 0.85 J/m2 for Y-doped nanoparticles. Diffusion coefficients calculated from coarsening curves for undoped and doped compositions at 850 °C were 4.8 × 10-12 cm2/s and 2.5 × 10-12 cm2/s, respectively, indicating the coarsening inhibition induced by Y3+ results from a combination of a reduced driving force (surface energy) and decreased atomic mobility.

An Alternative Approach for the Synthesis of Zinc Aluminate Nanoparticles for CO and Propane Sensing Applications

We implemented a simple and inexpensive aqueous sol-gel process to synthesize ZnAl2O4 nanoparticles to study its potential application as a gas sensor. Compared to traditional ceramic methods, the synthesis was conducted at lower temperatures and reaction times (5 h from 200 °C). The crystalline evolution of the oxide was investigated. The effect of the calcination temperature (200–1000 °C) on the crystallites’ size (16–29 nm) and the ZnAl2O4 powder’s surface morphology was also analyzed. Measurements confirmed the formation of bar-shaped granules (~0.35 μm) made up of nanoparticles (~23 nm). The surface area of the powders was 60 m2/g. Pellets were made from the powders and tested in sensing carbon monoxide and propane gases, showing a high sensitivity to such gases. The sensor’s response increased with increasing temperature (25–300 °C) and gas concentration (0–300 ppm). The oxide showed a higher response in propane than in carbon monoxide. We concluded that the ZnAl2O4 is a good candidate for gas sensing applications.

Experimental study of doped zinc aluminate nanoparticles by bottom-up approach for microstrip patch antenna applications

Experimental study of doped zinc aluminate nanoparticles by bottom-up approach for microstrip patch antenna applications

Zinc aluminate nanoparticles modified with (D-xylose, adenine)-derived nitrogen-doped carbon nanosheet composites as high-efficiency microwave absorbents

In this work, the ZnAl2O4/nitrogen-doped carbon nanosheet composites were prepared through a hydrothermal and pyrolysis method using D-xylose, adenine, zinc nitrate, and aluminum nitrate as raw materials. Results showed that a large number of interfaces inside the composite resulted in interfacial polarization and the formation of conductive networks between material particles, further increasing loss to microwaves; an appropriate ratio between reactants and the introduction of zinc aluminate can adjust the impedance matching of a material. When 0.2 g of nitrogen-doped carbon nanosheets was used, the minimum reflection loss was −40.8 dB at the sample matching thickness of 2 mm, and the maximum effective absorption bandwidth was 6 GHz.

Facile synthesis and complete characterization of Zn1-xSrxAl2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles using combustion technique

Zn1-xSrxAl2O4 (0 ≤ x ≤ 0.5) nanoparticles are successfully produced by combustion method. Powder XRD studies confirms the substitution of Sr2+ in ZnAl2O4 spinel nanostructure and average crystallite size lies between 32 to 39 nm. FTIR spectra revealed bands at 710 and 563 cm-1 corresponds to the intrinsic stretching vibrations of Mtetra–O atom which takes place at tetrahedral lattice sites and octahedral metal stretching Moctra–O appears as peak positioned at 498 cm-1 . HR-SEM images confirms spherical nanoparticles with agglomerated nature for strontium doped zinc aluminate nanoparticles. The presence of oxygen, aluminium, zinc and magnesium elements were confirmed from EDX spectra. The band gap of ZnAl2O4 was found to be 5.16 eV and the bandgap increases gradually with the increase in Sr2+ doping concentration. The magnetization plots were determined the super paramagnetic behaviour at room temperature.

Third order nonlinear optical behavior and optical limiting properties of Ni2+ ions doped zinc nano-aluminates

Nanosized Zn1-xNixAl2O4(0 ≤ x ≤ 0.5) particles were synthesized using microwave assisted combustion process with metal nitrates as starting precursors. The crystalline behavior of the synthesized samples is confirmed through the powder XRD and TEM studies. XPS studies are employed to obtain the oxidation state and the chemical elements details. HR-SEM analysis shows the morphology of agglomerated coalescence behavior. The elemental composition of Zn, Ni, O and Al was qualitatively obtained from EDX analysis. UV-DRS spectra are used to evaluate the optical band gap which is in the range of ̴ 5.45 to 3.32 eV. In FTIR spectra, two essential peaks n1 and n2 are endorsed the existence of spinel structured Zn1-xNixAl2O4 (0 ≤ x ≤ 0.5). The exothermic transitions and weight loss of elements is obtained by TG-DTA analysis. The magnetic parameters are confirmed the super paramagnetic behavior for all nickel doped zinc aluminate nanoparticles. The nonlinear optical properties are determined by Z-scan technique. It is found that the optical threshold values are in the range of 5.98, 5.25, 4.85 and 3.73 mW respectively. All the samples are exhibited the defocusing effect at CW laser.

Rare earth activated bio synthesis of zinc aluminate for photocatalytic activity of dye

The Dysprosium doped Zinc aluminate (ZnAl2O4) nanoparticles were prepared by green biogenic technique using Resinifera E-tirucalli latex. Nitrates of all precursors were used as starting materials. Naturally available Resinifera latex of Euphorbia family was used as a combustion agent. The samples prepared were calcined at 900 °C for three hours. The final calcined powders were analysed for X-ray diffraction to study the structural analysis and an average crystallite size was calculated to be around 18 nm using Scherrer’s and Williamson hall equation. Fourier Transform Infrared spectroscopy confirms the purity of the sample. The optical properties were determined by UV–Visible spectra. The photocatalytic activity of the ZnAl2O4:Dy3+ nanoparticles for the methylene blue dye was studied beneath solar source and UV light treatment by varying pH of the solution.

Correlation between degree of crystallinity and bluing of Zn1–xCoxAl2O4 (0≤x≤1) nanopowders prepared by soft chemistry route

In this article, we report a facile precursor pyrolysis by sol-gel method to prepare spinel-type Cobalt-substituted zinc aluminate nanoparticles (Zn1–xCoxAl2O4, 0 ≤ x ≤ 1). The relationship between the degree of crystallinity and the optical properties under the effect of the calcination temperature was investigated. The synthesised powders were characterized by means of X-ray diffraction (XRD), Thermogravimetry and Differential thermal analysis (TG–DTA), field emission scanning electron microscopy (FE-SEM), Brunauer–Emmett–Teller analysis (BET), UV–Vis absorption spectroscopy analysis and colorimetric analysis (CIELab). A single-phase Zn1–xCoxAl2O4 (0 ≤ x ≤ 1) spinel was formed at an annealing temperature of 700 °C. Structural refinement via the Rietveld method shows that an annealing temperature in excess of 700 °C leads to a decrease in the amorphous phase rate. At 800 °C, the enrichment in 50% of cobalt leads to blue powders with a degree of crystallinity of approximately 92% and a quasi-spherical morphology of nanometric size less than 100 nm.

Turning-on persistent luminescence out of chromium-doped zinc aluminate nanoparticles by instilling antisite defects under mild conditions.

Spinel oxide nanocrystals are appealing hosts for Cr3+ for forming persistent luminescent nanomaterials due to their suitable fundamental bandgaps. Benefiting from their antisite defect-tolerant nature, zinc gallate doped with Cr3+ ions has become the most studied near-infrared (NIR) persistent luminescent material. However, it remains challenging to achieve persistent luminescence from its inexpensive analogs, e.g., zinc aluminate (ZnAl2O4). Because the radius difference of the cations in the latter system is bigger, it is intrinsically unfavorable for ZnAl2O4 to form Zn-Al antisite defects under mild conditions. Herein, we report a wet-chemical synthetic route for preparing Cr3+-doped ZnAl2O4 nanoparticles with long NIR persistent luminescence. It was demonstrated that methanol (MeOH) as an important component of the mixed solvent played a critical role in tailoring the morphology of the resulting ZnAl2O4:Cr nanocrystals. It could particularly drive the formation of antisite defects in the resulting coral-like nanoparticles bearing zinc-rich cores and zinc gradient peripheries. To disclose the effects of MeOH on the formation of antisite defects as well as particle morphologies, small molecules released during the pyrolysis of metal acetylacetonate precursors were analyzed by using gas chromatography-mass spectrometry. In combination with density functional theory (DFT) calculations, it was found that MeOH can effectively catalyze the thermolysis of metal acetylacetonate precursors, in particular Zn(acac)2. Therefore, MeOH exhibits remarkable effects on the formation of antisite defects by balancing the decomposition rates of Zn(acac)2 and Al(acac)3 through its volume fraction in the reaction system. This work thus constitutes a hitherto less common strategy for achieving NIR persistent luminescence from Cr3+-doped ZnAl2O4 nanoparticles by engineering the cation defects under mild conditions.

Investigation of structural, optical and magnetic behavior of MAl2O4 (M= Zn and Co) nanoparticles via microwave combustion technique

Microwave combustion process is used to synthesize MAl2O4 (M = Zn and Co) spinel nanoparticles utilizing the fuel l-alanine. Synthesized samples were examined by techniques viz. XRD, HR-SEM, EDX, DRS-UV, PL, TG-DTA, FT-IR, XPS and VSM. The XRD confirmed the formation of cubic spinel structure with the average crystallite size of 14 nm and 11 nm for Cobalt and Zinc aluminate nanoparticles respectively. The morphology of CoAl2O4 (CAO) and ZnAl2O4 (ZAO) nanoparticles was observed by HR-SEM. EDX and XPS studies confirmed the formation of pure spinel aluminate structure. Further band gap values were estimated to be 3.35 and 5.45 eV for CAO and ZAO respectively. The PL spectra of CAO and ZAO nanoparticles were studied with an excitation wavelength of 235 and 205 nm. The strong absorption bands between 500-1100 cm-1 were linked to CAO and ZAO nanoparticles. TG-DTA analysis confirmed weight loss and exothermic transitions. The M − H loops revealed CoAl2O4 and ZnAl2O4 nanoparticles exhibited superparamagnetic behavior.

Rapid Synthesis and Characterization of Pure and Cobalt Doped Zinc Aluminate Nanoparticles via Microwave Assisted Combustion Method.

Zn1-xCoxAl₂O₄ (0 ≤ x ≤ 0.5) nanoparticles were synthesized employing L-alanine as fuel using MACT (microwave assisted combustion technique). The synthesized samples were characterized following methods such as X-ray Diffraction, high resolution scanning electron microscopy, Energydispersive X-ray spectroscopy; UV-visible diffused reflectance spectroscopy, FT-IR and VSM. The XRD confirmed the cubic spinel structure and the average crystallite size observed lying in the range of 12-19 nm deduced using the Debye Scherrer's equation. The morphology of the Zn1-xCoxAl₂O₄ (0 ≤ x ≤ 0.5) nanoparticles is observed using HR-SEM. EDX analysis is opted for the elemental mapping of pure and cobalt doped zinc aluminate nanoparticles. Further band gap value was calculated using Kubelka Munk function, which was seen lying within 3.73 to 5.45 eV. The strong absorption band at 669, 556 and 500 cm-1 was associated with the vibrations of Zn-O, Al-O and Zn-O-Al of zinc aluminate nanoparticles. The hysteresis loops exhibited conversion from diamagnetic into super paramagnetic behaviour with increase in Co doping.

Zinc aluminate nanoparticles: Preparation, characterization and application as efficient and economic catalyst in transformation of waste cooking oil into biodiesel

In this study, an efficient and economic transesterification process for waste cooking oil (WCO) using methanol was contemplated. The process was preceded using zinc aluminate nanoparticles as heterogeneous catalyst. High purity porous ZnAl2O4 nanoparticles with polycrystalline nature were effectively prepared using co-precipitation technique at two annealing temperatures of 700 and 800 °C. The prepared ZnAl2O4 nanoparticles were described using FTIR, XRD, EDX, and SEM spectroscopy. The structure, morphological and chemical properties of the ZnAl2O4 catalyst annealed at 800 °C showed high reactivity compared to that annealed at 700 °C. The transesterification process parameters were studied, including catalyst dose, conversion temperature, time of the process, and the ratio of oil to methyl alcohol. The optimized process conditions were produced a maximum biodiesel yield of 94.88% after 3 h at 100 °C using 5 wt% catalyst and 1:18 oil/methanol ratio. The physicochemical properties of the obtained biodiesel were in accordance with the biodiesel standards D-6571 (ASTM) and the Egyptian standards EN 14214.

Impact of Mg2+ Ion on the Structural, Morphological, Optical, Vibrational, and Magnetic Behavior of Mg:ZnAl2O4 Spinel

In this work, Magnesium-doped zinc aluminate nanoparticles are synthesized using microwave combustion technique by employing L-alanine as fuel. The incorporation of Mg2+ ions plays a pivotal role in influencing the optical, structural, and magnetic properties of zinc aluminate nanoparticles. The synthesized nanoparticle are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM).The XRD patterns confirmed the formation of single-phase cubic spinel structure of ZnAl2O4 (gahnite). The average crystallite sizes estimated from Debye-Scherrer is found to be in the range of 6 to 12 nm. HR-SEM images revealed the spherical morphology with uniform distributions. The optical bandgap of the synthesized nanoparticles is found to be in the range of 5.45 eV–5.76 eV. Magnetic measurement reveals that pure and doped zinc aluminate nanoparticles have superparamagnetic nature. These obtained results of Zn1-xMgxAl2O4 (0 ≤ x ≤ 0.5) are found to be well suited for optoelectronics, magnetic, and catalytic applications.

Catalytic activity of bismuth doped zinc aluminate nanoparticles towards environmental remediation

In the current work, zinc aluminate and bismuth doped zinc aluminate (ZnAl2-xBixO4, x=0, 0.05, 0.1) spinel oxide nanoparticles were synthesized by co-precipitation method. The obtained samples were characterized by powder XRD, FT-IR, DRS, SEM-EDX and BET. Photocatalytic degradation of zinc aluminate and bismuth doped zinc aluminate nanoparticles were investigated using methylene blue as a model pollutant under UV light. 98. 28% of photodegradation of methylene blue was achieved in 150min using the bismuth doped zinc aluminate catalyst. The reduction of 4-nitrophenol to 4-aminophenol was completed within 7s using bismuth doped catalyst.

Synthesis and characterization of ZnAl2O4 spinel from Zn(II) and Al(III) carboxylates

In this paper, zinc aluminate (ZnAl2O4) nanoparticles were obtained by a new synthesis method, thermal decomposition of Zn(II) and Al(III) carboxylates mixture. Complex combinations were obtained in the redox reaction between Zn(NO3)2·6H2O, Al(NO3)3·9H2O, and 1,3-propanediol at ~130 °C. The mechanism of Zn(II) and Al(III) carboxylates formation and decomposition was observed by thermal analysis and Fourier transform infrared spectroscopy. Zn(II) carboxylate, Al(III) carboxylate, and Zn(II) and Al(III) carboxylates mixture were annealed at different temperatures. Metal oxides synthesized from carboxylates precursors in single metal systems crystallized very well at 400 °C (ZnO) and weak at 800 °C (Al2O3), as shown by X-ray powder diffractometry. Homogenous mixture of Zn(II) and Al(III) carboxylates heated at 400 °C has led to a mixture of amorphous ZnO and Al2O3, which reacted forming at 600 °C well-crystallized ZnAl2O4, with mean crystallites size of 14.2 nm. The decomposition of carboxylates precursors is an appropriate method to obtain ZnAl2O4 spinel as well-crystallized single phase at low temperatures.

Structural, optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl2O4:Ce3+) increased the photocatalytic activity of zinc aluminate.

Synthesis of mesoporous metal aluminate nanoparticles and studies on the decontamination of sulfur mustard

Magnesium, calcium, cobalt, nickel, copper, and zinc aluminate nanoparticles were synthesized by co-precipitation method. They were characterized by transmission electron microscopy, X ray diffraction, scanning electron microscopy coupled with energy dispersive analysis of X rays, nitrogen adsorption techniques. Transmission electron microscopy data indicated the formation of mesoporous metal aluminate nanoparticles with particle size ranging from 5 to 100 nm. X ray diffraction data indicated the formation of metal aluminate nanoparticles with spinel structure. Nitrogen adsorption data of metal aluminate nanoparticles illustrated mesoporosity with the values of surface area ranging from 63 to 325 m2/g. These mesoporous metal aluminate nanoparticles were used for decontamination of sulfur mustard and the decontamination reactions exhibited first order behavior. Magnesium aluminate nanoparticles showed greater decontamination efficiency relative to other ones and decontaminated 100% of sulfur mustard within 4 h where others took more time to completely degrade it. The promising decontamination properties of metal aluminates nanoparticles against sulfur mustard were attributed to the basic sites, Lewis acid sites and the presence of these sites was confirmed by CO2 and NH3 temperature programmed desorption.