Metal-oxygen Vibrations Research Articles

Exploring structural and optical properties of iodine-doped TiO2 nanoparticles in Rhodamine-B dye degradation: Experimental and theoretical investigation

Energy conversion and pollutant degradation are critical for advancing sustainable technologies, yet they often encounter challenges related to charge recombination and efficiency limitations. This study explores iodine-doped TiO2 nanoparticles as a potential solution for enhancing both energy conversion and pollutant degradation. The nanoparticles were synthesized via the sol-gel method with varying iodine precursor concentrations (0.025–0.1 M) and were characterized for their structural, compositional, and optical properties, particularly in relation to their photocatalytic performance in Rhodamine-B dye degradation. X-ray diffraction confirmed a tetragonal anatase crystal structure, with the average crystallite size decreasing from 10.06 nm to 8.82 nm with increase in iodine concentration. Selected area electron diffraction patterns verified the polycrystalline nature of the nanoparticles. Dynamic light scattering analysis showed hydrodynamic radii ranging from 95 to 125 nm. Fourier-transform infrared spectroscopy identified metal-oxygen vibrations at 441 cm⁻1, and electron microscopy confirmed the spherical morphology of the nanoparticles. Elemental analysis detected the presence of Ti, O, and I in the samples. Diffuse reflectance spectroscopy indicated the optical absorption edges for the doped samples in the visible region from which the corresponding band gap values were deduced. Photoluminescence spectroscopy revealed that the sample with 0.1 M iodine exhibit the lowest emission intensity, suggesting reduced charge recombination. Notably, 0.1 M iodine doped TiO2 samples demonstrated the highest photocatalytic efficiency, achieving 82.36% degradation of Rhodamine-B dye within 140 min under visible light. Additionally, ab-initio density functional theory calculations were performed to investigate the structural, optical, and adsorption properties of TiO2, iodine-doped TiO2, Rhodamine-B, and their composites, providing further insight into the enhanced photocatalytic activity observed in the experiments.

Facile synthesis, enhanced annealing-structural investigation and supercapacitive potentials of NiFe2O4 spinel nanopowder

Herein, we examined and optimized the influence of annealing temperature on microstructural and electrochemical charge storage properties of spinel NiFe2O4 nanopowder synthesized from a simple one-pot sol-gel route. Microstructural techniques encompassing Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, x-ray diffractometry, and Fourier transform infra-red spectroscopy indicate the resulting powder are composed of spinel NiFe2O4 nanoparticle with metal oxygen vibration, crystal properties and lattice strain, all dependent on annealing temperature. Electrochemical charge storage performance of the electrode fabricated from the synthesized material were investigated with the aid of cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The obtained results showed that the charge storage performance and rate capability of NiFe2O4 electrode is dependent on the annealing temperature. The study also showed that the electrode from the material annealed at 400 °C demonstrated optimum electrochemical charge storage performance having exhibited optimum specific capacitance and capacity values of 1128 Fg−1 and 58 mAh g−1 at 5 mVs−1 scan rate and 0.5 Ag−1 current density, respectively. The electrode EIS fitted equivalent circuit values were also found dependent on annealing temperature indicating the charge transfer process and rate capability of spinel NiFe2O4 nano-powder can be tailored by simply varying the annealing temperature. The study demonstrates cheap route by which spinel NiFe2O4 powder can be prepared. It also unveils the effect annealing temperature on the microstructural build-up and electrochemical charge storage performance of the material.

Effect of Cd on Structural, Spectral, Morphological and Dielectric Properties of Sr1-xCdxZn2Fe4O11 R-type Hexaferrites Synthesized via Sol-gel Technique

Sol–gel method was used to prepare Sr1-xCdxZn2Fe4O11 (x = 0.00, 0.02, 0.06, 0.1) R-type hexaferrite. The synthesized materials were sintered at 850oC and desired phase was obtained. X-ray diffraction analysis confirms that R-type hexaferrite exists only as a single phase. Using the Scherer formula, crystallite size for all of the prepared samples was found to be in the range of 10.39–12.62 nm. Crystallite size (D), the lattice parameters (a, c), and the cell volume (Vcell), d-spacing, bulk density, X-ray density, porosity, dislocation density and micro strain were determined in structural analysis. Fourier transform infrared spectroscopy method was used to identify the metal-oxygen vibrations at different locations. FT-IR verifies the presence of the Fe–O stretching vibration band at 743 and 867 cm−1. The typical grain size in surface morphology investigation ranges from 0.56 to 0.82 μm. Dielectric response of ferrite ceramic samples replaced with Cd2+ was investigated in the frequency range of 1 MHz–3 GHz. The AC conductivity rises with an increase in frequency because they are proportional to one another. This increasing tendency is effectively described by the theory of Maxwell-Wagner and Koop. Q-values remain constant as frequency rises and behaves independently of frequency as long as frequency reaches 1.7 GHz. These types of materials are utilized in high-frequency applications including frequency filters and resonant circuits. All of the magnetic properties determined by analyzing the M − H loops, including saturation magnetization (Ms), retentivity (Mr), and coercivity (Hc), exhibit an increasing trend as the substitution of Cd2+ rises. Ms (49.76–56.38 emu/g), Mr (15.82–18.30 emu/g) and Hc range from 203.20 Oe to 215.80 Oe. Grain size decreases cause arise in coercivity, which is caused by an enhancement in magneto-crystalline anisotropy. Overall results suggest that Cd2+ replaced R-type hexagonal ferrites are a great resource for longitudinal recording media; they have the potential to be used in a wide variety of electronic applications, including resonant circuits and high-frequency filters, security, detecting and switching.

Synergistic effects of TiO2-ZnO/Poly(methyl methacrylate) nanocomposite films: Enhanced wettability, antimicrobial activity, and biocompatibility

The poly (methyl methacrylate) (PMMA) nanocomposite films were fabricated using a cost-effective solvent evaporation method. The dominance of the wurtzite Zinc oxide (ZnO) phase was observed, accompanied by a suppression in the phase intensity of anatase titanium dioxide (TiO2) in the PMMA matrix confirmed by the XRD. New peaks appeared at 1651 cm−1 for the Ti-OH of TiO2 and 590 cm−1 for the metal–oxygen vibration of ZnO in the nanocomposite films. SEM micrograph of the TZPMMA resulted in the formation of nanopores with the nanoparticles embedded in the PMMA matrix. The wettability was enhanced by 23 % with the incorporation of metallic nanoparticles. Zinc ions increased antimicrobial susceptibility against S. aureus by 20 % more than E. coli, demonstrating the potential for fighting bacterial infections. The porous surface created by the nanoparticles improved the cell viability of the PMMA. Zebrafish embryo mortality percentage (0.5 %) and cell viability percentage (80 %) against human gingival fibroblasts (hGFs) showed that the incorporation of metal oxides made the PMMA, a potential candidate for biomedical applications.

Enhanced Structural and Electrochemical Properties of Zn-Doped NiCo2O4 Synthesized by Low-Temperature Microwave Hydrothermal Process

The specific capacitance (Cp) is an important parameter influencing the energy storage capacity of materials. In this study, a series of NiZn x Co2-x O4 (x = 0.0–0.10) nanoparticles were prepared using the microwave-hydrothermal (M-H) method. The samples were characterized by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical studies. It is observed from X-ray diffraction that all the samples are cubic in nature with space group Fd-3m. The average lattice constant is varied in between 7.63 (x = 0.0) to 8.34 (x = 0.10). The linear increase in lattice constant is due to the difference in the ionic radii. The average grain size is in the range of 80 (x = 0.0) − 124 nm (x = 0.10) for all the samples, and grains are found to be spherical in nature. The characteristic metal oxygen vibration bands were observed at 578 cm−1 and 661 cm−1. The valence states of Ni2+/Ni3+, Co2+/Co3+ and Zn2+ were confirmed by X-ray photoelectron spectroscopy. The electrochemical studies were performed on all the samples. The high value of specific capacitance (Cp) 871.91 Fg−1 is observed for sample x = 0.06. Therefore, Zn doped NiCo2O4 shows good impedance and electrochemical properties which is promising material for supercapacitor applications.

Spectroscopic, Magnetic and Morphological studies of MgFe2O4 Nanopowder

Spinel type nano ferrite compound MgFe2O4 was synthesized through sol gel technique using metal nitrates as precursors. The phase composition, morphology and elemental analysis of magnesium ferrite (MgFe2O4) were performed by X-ray diffraction, fourier transform infrared, atomic force microscopy, energy dispersive x-ray and scanning electron microscopy, analyses. 
 The sample's X-ray diffraction pattern verifies the existence of single phase material, with the size of its crystallites estimated to be 39.9 nm. Fourier transform infrared examination supported metal-oxygen vibrations corresponding to tetrahedral and octahedral sites, respectively. From scanning electron microscopy image, grain size obtained about 97.7 nm. Raman spectra of the sample shows five Raman active modes (A1g + Eg + 3F2g), which is compatible with the spinel structure. Magnetic measurement study at room temperature shows a hysteresis loop behaviour with a low saturation magnetization value, 27.192 emu g-1 and a small coercivity value. The optical band gap determined using UV-visible transmittance spectra. Additionally, X-ray photoelectron spectroscopy are used to confirm oxidation states and explore the chemical composition of the sample.

Degradation of cefadroxil drug by newly designed solar light responsive alcoholic template-based lanthanum ferrite nanoparticles

In this work, lanthanum ferrite nanoparticles were synthesized via a simple co-precipitation method. Two different templates, namely sorbitol and mannitol, were used in this synthesis to tune the optical, structural, morphological, and photocatalytic properties of lanthanum ferrite. The synthesized lanthanum ferrite-sorbitol (LFOCo-So) and lanthanum ferrite-mannitol (LFOCo-Mo) were investigated through Ultraviolet–Visible (UV–Vis), X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR), Raman, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), and photoluminescence (PL) techniques to study the effects of the templates on the tunable properties of lanthanum ferrite nanoparticles. The UV–Vis study revealed a remarkably small bandgap (2.09 eV) of LFOCo-So compared to the LFOCo-Mo having a band gap of 2.46 eV. XRD analysis revealed a single-phased structure of LFOCo-So, whereas LFOCo-Mo showed different phases. The calculated crystallite sizes of LFOCo-So and LFOCo-Mo were 22 nm and 39 nm, respectively. FTIR spectroscopy indicated the characteristics of metal-oxygen vibrations of perovskites in both lanthanum ferrite (LFO) nanoparticles, whereas a slight shifting of Raman scattering modes in LFOCo-Mo in contrast to LFOCo-So showed the octahedral distortion of the perovskite by changing the template. SEM micrographs indicated porous particles of lanthanum ferrite with LFOCo-So being more uniformly distributed, and EDX confirmed the stoichiometric ratios of the lanthanum, iron, and oxygen in the fabricated lanthanum ferrite. The high-intensity green emission in the photoluminescence spectrum of LFOCo-So indicated more prominent oxygen vacancies than LFOCo-Mo. The photocatalytic efficiency of synthesized LFOCo-So and LFOCo-Mo was investigated against cefadroxil drug under solar light irradiation. At optimized photocatalytic conditions, LFOCo-So showed higher degradation efficiency of 87% in only 20 min than LFOCo-Mo having photocatalytic activity of 81%. The excellent recyclability of the LFOCo-So reflected that it could be reused without affecting photocatalytic efficiency. These findings showed that sorbitol is a useful template for the lanthanum ferrite particles imparting outstanding features, enabling it to be used as an efficient photocatalyst for environmental remediation.

Investigation of crystal structure, electrical and dielectric response of Ga3+ substituted Sr–Ni Y-type hexaferrites as a suitable material for high frequency applications

Technology important ferrites ceramic Sr2Ni2GaxFe12-xO22 (x = 0.00, 0.2, 0.4, 0.6, and 0.8) samples were produced using sol-gel auto combustion route. Structural, electrical, dielectric, and magnetic parameters were identified by substituting Ga3+ at the Fe3+ site. It was recognized that an increase of Ga3+ content in (Sr2Ni2GaxFe12-xO22) ceramic samples first decreased, then increased lattice parameters, and the density of samples was observed. This is because of the ionic radii and atomic weight of Ga3+ and Fe3+ cations. FTIR spectra show two characteristic absorption bands at 444-513 cm−1 caused by metal-oxygen vibrations. Due to the contribution of smaller grains of samples, the higher values of resistivity were observed, which vary from 3.78 × 1010 (Ω cm) to 1.13 × 1011 (Ω cm) by the substitution of Ga3+ ions at the octahedral site. The activation energy was measured between 0.20 and 0.61 eV. The dielectric response of Ga3+ substituted ferrite ceramic samples were studied in the 1 MHz-6 GHz frequency region. The Maxwell-Wagner bilayer model studied the effect of polarization with applied frequency on dielectric parameters. With the substitution of Ga3+, minimal losses in the range 0.34–0.44, about 6 GHz, and a high Q-value of about 10,000 were observed for each sample. In impedance spectroscopy analysis Cole-Cole plots confirm that the dielectric response is because of the influence of grain boundaries. The substitution of Ga3+ enhances saturation magnetization (68.20–71.78 emu/g) while coercivity decreases (655.86–507.86 Oe). In the present finding, the low dielectric loss, moderate permittivity, high value of the Quality factor, and very high value of resistivity of about 1.13 × 1011 that reduces the eddy current losses suggested that these materials are appropriate candidates for many high-frequency applications such as multilayer chip inductor, dielectric resonators, power applications, and microwave devices.

Water-in-Oil Pickering Emulsions Stabilized by Divalent Metal Phenylphosphonate Particles

Phenylphosphonates of zinc (Zn-PPh), calcium (Ca-PPh) and magnesium (Mg-PPh) were synthesized by the hydrothermal method. Samples showed characteristic X-ray diffraction (XRD) patterns of layered compounds with basal spacing in the range of 14-15 Å. According to Fourier transform infrared spectroscopy (FTIR), all compositions showed the presence of characteristic bands attributed to phenyl aromatic rings, phosphonate and lattice metal-oxygen (M-O) vibrations. Different concentrations of phenylphosphonate particles were applied to stabilize water-in-oil Pickering emulsions using vaseline oil in different w/o fractions. The three particle types showed greater affinity for the oil phase (wettability) and the ability to stabilize the emulsions via the Pickering effect. Ca-PPh particles contained a greater emulsified fraction after 20 days of evaluation. This result can be attributed to the particle morphology observed by scanning electron microscopy (SEM). The fibrous morphology of Ca-PPh particles is believed to increase the steric hindrance effect at the surface around the droplets, while the Zn-PPh and Mg-PPh layered particles tended to form clusters.

Luminous LaAlO3 :Dy3+ perovskite nanomaterials: Synthesis, structural, and luminescence characteristics for white light-emitting diodes.

A single-phase perovskite LaAlO3 :Dy3+ phosphor was synthesized using a gel-combustion method at 600°C utilization with hexamethylenetetramine as a fuel. Further calcination of the samples was carried out (800 and 1000°C) to investigate the resultant effect on the crystalline and luminescence behaviour. The crystal structure had a cubic unit cell (space group Pm3̅m) and was examined using the Rietveld refinement and X-ray diffraction data. Additionally, Debye-Scherrer and Williamson-Hall equations were applied to determine other structural features. The particle size and morphology of phosphors were evaluated using transmission electron microscopy. Diffraction measurements were supported by the various metal-oxygen vibration modes studied with the help of Fourier transform infrared spectroscopy. Energy-dispersive X-ray analysis verified the chemical composition of synthesized sample. Luminescence spectra of the LaAlO3 :Dy3+ phosphors exhibited intense bands for 4 F9/2 →6 H15/2 (482 nm, bluish region) and 4 F9/2 →6 H13/2 (574 nm, yellowish region) transitions. Commission Internationale de L'Eclairage and correlated colour temperature data confirmed the cool-white emission of the samples under ultraviolet light excitation. The interesting and advantageous luminescence characteristics of LaAlO3 :Dy3+ phosphors make them potential materials for white light-emitting diodes.

Energy-levels well-matched direct Z-scheme ZnNiNdO/CdS heterojunction for elimination of diverse pollutants from wastewater and microbial disinfection.

Energy-levels well-matched direct Z-scheme ZnNiNdO/CdS heterojunction was successfully fabricated using facile co-precipitation and ultra-sonication techniques and characterized with XRD, FTIR, Raman, PL, UV-vis, and FE-SEM. The XRD diffractograms confirmed the co-doping of Ni-Nd in ZnO and the formation of heterostructured nanocomposite. FTIR and Raman data showed the presence of metal-oxygen vibration and optical phonon modes of ZnO and CdS. FE-SEM images exhibited the network type morphology. The energy bandgap was redshifted by co-doping (3.37-2.9eV) and was further reduced (2.6eV) by making a composite with CdS. The ZnNiNdO/CdS catalyst degraded 99.7, 49, 96.6, 98.6, and 98.6% methylene blue (MB), p-nitroaniline (P-Nitro), methyl orange (MO), methyl red (MR), and rhodamine B (RhB) dyes under 50min sunlight irradiation. Moreover, ZnNiNdO/CdS showed intense inhibition activity towards Staphylococcus aureus, Escherichia coli, Proteus vulgaris, and Pseudomonas aeruginosa bacterial strains with maximum inhibition zone diameters 30, 33, 27, and 31mm, respectively. The synergistic effects arising from band alignment can lead to efficient vectorial charge separation, transportation, and lower recombination of photoinduced charge carriers, ultimately boosting photocatalytic and antibacterial performance. The ZnNiNdO/CdS photocatalyst has higher stability up to the 7th cycle towards MB dye with ~ 5% deficit in degradation efficiency. The higher generation of superoxide and hydroxyl radical was confirmed by species trapping experiments responsible for photodegradation of dyes molecules. Furthermore, the results showed that the photocatalytic and antibacterial performance of pristine ZnO can be enhanced by co-doping and tuning energy bandgap.

Effect of sintering temperature on the magnetic properties of ZnFe2O4 composite with cobaltic oxide synthesized by chemical co precipitation method

The present studies reports the synthesis of Zinc ferrite (ZnFe2O4) composite with cobaltic oxide (Co3O4) by chemical co precipitation method. Sintering of the as synthesized sample has been done in a conventional furnace having heating rate of 5 °C per minute at three different sintering temperatures namely 600 °C, 750 °C, 900 °C. X-ray Diffraction (XRD) analysis shows the presence of cubic spinel ferrites with increasing crystallite size with the increase of sintering temperature. FTIR reveals the presence of absorption band due to metal oxygen vibrations. VSM measurement reveals the magnetic properties of ZnFe2O4 composite enhances thereby obtaining the maximum values of magnetization, coercivity and retentivity at 900 °C. The values of magnetization at 15.5 kOe, coercivity and retentivity observed were 19.355 emu/gm, 14.507 Oe and 0.24802 emu/gm respectively for the composite sintered at 900 °C. The understanding regarding the variation in the magnetization is discussed.

Effect of Ni2+ substitution on DC electrical conductivity and magnetic properties of Ba1-xNixFe2O4 synthesized by citric acid gel method

The synthesis of Ba1-xNixFe2O4 (with x = 0.04, 0.08, 0.12) spinel ferrites were carried out by citric acid gel combustion method. Effect of Ni2+ substitution in Ba1-xNixFe2O4 ferrite lattice on its structural, magnetic, optical and electrical properties has been investigated by using XRD, FT-IR, VSM, UV-Vis.-DRS and DC electrical conductivity respectively. The single-phase orthorhombic spinel structure XRD results were confirmed with Pmcn space group. Decrease in lattice constant and unit cell volume is observed with the increase in Ni content. IR spectroscopy confirmed the existence of metal oxygen vibrations. M−H loops from VSM studies attributed the magnetization ranging from 0.1483 to 5.5969 emu/g and drastic changes in coercivity from 1220 to 2633 Oe is observed. Optical analysis and DC conductivity attributed decrease in band gap energy as well as activation energy respectively.

Unveiling the effect of Gd–Co co-substitution in the enrichment of structural and dielectric properties of SrBaMn based magnetic oxide

Nano-crystalline Gd–Co substituted X-type hexagonal ferrites having formula SrBaMn2-xCoxGdyFe28-yO46 (where x = 0–1, y = −0.1) were synthesized employing sol-gel route. X-ray diffraction technique verified the formation of pure phase X-type ferrites for all samples. Crystallite size was reduced from 27.49 to 24.52 nm with Gd–Co concentration, which is favorable for attaining an appropriate signal-to-noise ratio in electronic devices. Lattice constants (a, c), bulk, and X-ray density slightly increased owing to the large ionic radius and density of Gd3+ ions than Fe3+ ions. Fourier transform infra-red spectroscopy displayed absorption bands in the lower wavenumber range (482-584 cm−1). The higher absorption bands (482-584 cm−1) are due to metal-oxygen vibration octahedral and tetrahedral sites. The influence of Gd–Co on dielectric properties such as dielectric constant, tangent loss, ac conductivity, and Q-value on frequency and composition were investigated in the frequency region of 1 MHz–3 GHz. The incorporation of Gd–Co resulted in the enhancement of dielectric properties of as-prepared X-type materials desired in electromagnetic devices operating at microwave frequencies. Electric modulus analyses indicated the contribution of grain boundary towards resistance.

Enhancement in carrier separation of ZnO-Ho2O3-Sm2O3 hetrostuctured nanocomposite with rGO and PANI supported direct dual Z-scheme for antimicrobial inactivation and sunlight driven photocatalysis

In this work, a direct dual Z-scheme ZnO-Ho2O3-Sm2O3 (NC), polyaniline PANI-ZnO-Ho2O3-Sm2O3 (NCP), and reduced graphene oxide rGO-ZnO-Ho2O3-Sm2O3 (NCR) heterostructure nanocomposites were fabricated successfully. The XRD diffractograms confirmed that ZnO has hexagonal, while Ho2O3, and Sm2O3 have cubic phases in all grown composites. FTIR data exhibited the existence of the PANI, rGO, and metal–oxygen vibration. Raman spectra revealed the presence of optical phonon modes of individual oxides in nanocomposites. PL results disclose the lower charge carrier recombination rate in NCR. SEM images confirmed the anchoring of roughly spherical nanoparticles of NC with PANI and rGO. The UV–Vis analysis showed that the optical energy bandgap was 2.95 eV, 2.88 eV, and 2.81 eV for NC, NCP, and NCR, respectively. The EIS results exhibited a lower charge transfer resistance of NCR than others. The photocatalytic performance against MB, MR, and P-Nitro dyes under sunlight exhibited NCR > NCP > NC efficiency for all dyes in 60 min. The recyclability tests have confirmed the reusability upto six cycles. The antibacterial activity against E. coli, S. aureus, and P. Vulgarisbacteria displayed a higher activity for NCR. The boosted photocatalytic and antibacterial performance of NCR have ascribed the existence of Z-scheme supported with rGO, promote electron/hole separation and hinder the charge carrier’s recombination. The results clearly demonstrate that the as-grown nanocomposites can be used as an effective material for bacterial disinfection and wastewater treatment.

Annealing temperature effect on cobalt ferrite nanoparticles for photocatalytic degradation

In this work, cobalt ferrite nanomaterials was prepared employing simple co-precipitation technique and annealed at 300, 400 and 600 °C. XRD study revealed the formation of cubic structure of CoFe2O4 nanoparticles and confirmed by high intense peak at 2θ value of 35.3°. The creation of ferrite phase was further confirmed by the studies such as FTIR, Raman and PL spectra. FTIR spectra confirmed the occurrence of Fe–O and Co–O metal oxygen vibrations and the lattice defects and oxygen vacancies of the CoFe2O4 nanoparticles were explored by PL spectra. No other signals were detected in Raman spectra, which explored pure spinal ferrites. The energy band gap values are obtained by using Tauc plot and the obtained band gap values for all the cobalt ferrite nanoparticles were 2.84, 2.75 and 2.89 eV respectively. The morphology of synthesized cobalt ferrite nanomaterials were observed from the SEM and TEM images. The product annealed at 400 °C showed the better morphology with least amount of agglomeration in comparison to other SEM images. In addition, SAED pattern of magnetic nanoparticles confirmed the existence of polycrystalline nature of the CoFe2O4 nanoparticles. The obtained surface area of CF2 sample was 5.082 m2 g−1 and pore volume and diameter of CF2 sample was found to be 0.013 cc/g and 3.937 nm respectively. Then, the product annealed at 400 °C exhibited most excellent activity and degraded 74% of cationic dye in 80 min, and it also exhibited excellent stability even maintain in three cycles.

Investigation on (Zn) doping and anionic surfactant (SDS) effect on SnO2 nanostructures for enhanced photocatalytic RhB dye degradation

Herein we reported the effect of doping and addition of surfactant on SnO2 nanostructures for enhanced photocatalytic activity. Pristine SnO2, Zn–SnO2 and SDS-(Zn–SnO2) was prepared via simple co-precipitation method and the product was annealed at 600 °C to obtain a clear phase. The structural, optical, vibrational, morphological characteristics of the synthesized SnO2, Zn–SnO2 and SDS-(Zn–SnO2) product were investigated. SnO2, Zn–SnO2 and SDS-(Zn–SnO2) possess crystallite size of 20 nm, 19 nm and 18 nm correspondingly with tetragonal structure and high purity. The metal oxygen vibrations were present in FT-IR spectra. The obtained bandgap energies of SnO2, Zn–SnO2 and SDS-(Zn–SnO2) were 3.58 eV, 3.51 eV and 2.81 eV due to the effect of dopant and surfactant. This narrowing of bandgap helped in the photocatalytic activity. The morphology of the pristine sample showed poor growth of nanostructures with high level of agglomeration which was effectively reduced for other two samples. Product photocatalytic action was tested beneath visible light of 300 W. SDS-(Zn–SnO2) nanostructure efficiency showed 90% degradation of RhB dye which is 2.5 times higher than pristine sample. Narrow bandgap, crystallite size, better growth of nanostructures paved the way for SDS-(Zn–SnO2) to degrade the toxic pollutant. The superior performance and individuality of SDS-(Zn–SnO2) will makes it a potential competitor on reducing toxic pollutants from wastewater in future research.

Catalytic and photocatalytic properties of zinc-nickel ferrites

A synthetic procedure combining high energy ball-milling and calcination at 900 °C was applied to obtain mixed metal oxides of the type Zn1−xNixFe2O4 (x = 0.25; 0.5; 0.75). The formation of spinel-like structures and the phase composition were confirmed by XRD in combination with Mossbauer, IR and Raman spectroscopy. The crystallite size was analysed from X-ray diffraction data revealing nanometric crystallites with an average size in the interval 20–60 nm. The IR spectra showed two fundamental absorption bands in the range 650–400 cm−1, which are characteristics of the metal-oxygen vibrations in tetrahedral and octahedral configurations. The mixed metal oxides were tested as catalysts for the decomposition of methanol to syngas and the degradation of the water pollutant malachite green in model solutions under UV light irradiation. Both the catalytic and photocatalytic activities were found to increase with increasing content of Ni(II) in the mixed metal oxides. The reduction behaviour of the samples was characterized by temperature-programmed reduction—thermogravimetric analysis and related to the catalytic conversion of methanol in the presence of the oxides. The most active samples for malachite degradation had the lowest band gap energy of 1.43 and 1.45 eV. The measurements of the reaction liquor by atomic absorption spectroscopy verified the stability of the samples tested as photocatalysts during the photocatalytic test. Zn/Ni ferrites of the type Zn1−xNixFe2O4 (x = 0.25; 0.5; 0.75) active both as catalysts for methanol conversion (a) and malachite green decomposition in model solutions under UV light irradiation (b)

Al-doped zinc ferrite nanoparticles: Preparation and evaluation of thermal, structural, morphological and anticancer properties

The aim of this study was to evaluate the thermal, structural, optical, morphological and anticancer properties of ZnFe2O4 (ZFO) and AlxZn1−xFe2O4 (x = 0.05) (ZAFO) nanoparticles. Zinc ferrite nanoparticles were prepared by chemical co-precipitation method, using polyethylene glycol (PEG) as the capping agent. The synthesized pure and Al-doped ZnFe2O4 nanoparticles were annealed at different temperatures such as 500, 600, 700 and 800 °C. X-ray diffraction analysis was used to determine lattice parameters like X-ray density, oxygen position parameter, distribution of cation among tetrahedral and octahedral sites, ionic radii, and edge lengths of the tetrahedral (A) and octahedral (B) sites and micro strain values. The calculated micro strain values were found to be decreasing with increasing annealing temperatures in both ZnFe2O4 and AlxZn1−xFe2O4 (x = 0.05) samples. The FTIR results confirmed ferrites tetrahedral (~540 cm−1) and octahedral sites (~431 cm−1) metal oxygen vibrations. The morphology of the synthesized ZnFe2O4 and AlxZn1−xFe2O4 (x = 0.05) nanoparticles were studied by field emission scanning electron microscopy (FE-SEM) and particle size was found to be<100 nm. Band gap energy at different temperatures were calculated using Tauc plots and found to be decreasing with increase in annealing temperatures for both ZnFe2O4 and AlxZn1−xFe2O4 (x = 0.05) nanoparticles. The anti-cancer properties were observed at the in vitro level by MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyltetrozolium bromide) assay against human Breast cancer cell line, MCF-7 (Human Breast adenocarcinoma) and lung cancer cell line A549 (Human Lung Carcinoma). Among the pure and Al doped samples used in the present study, the ZnFe2O4 (ZFO-3) sample annealed at 700 °C showed less viability in A 549 (Human Lung Carcinoma), whereas AlxZn1−xFe2O4 (ZAFO-1) sample annealed at 500°C showed less viability in MCF-7 (Human Breast Adenocarcinoma). Toxicity studies have shown that ZnFe2O4 and AlxZn1−xFe2O4 (x = 0.05) NPs reduced cell viability and induced cell membrane damage dose dependently in the concentration range of 25–100 µg/mL

External magnetic field effects on the characteristics of cobalt nanoparticles prepared by pulsed laser ablation

Effects of DC magnetic field in the range of 0–180 mT on the properties of cobalt oxide nanoparticles (Co3O4 NPs) synthesized by pulse laser ablation method in distilled water has been investigated. Ablation was carried out in the presence of permanent magnets with variable strengths. Significant blue shift in excitonic absorption peaks of produced nanoparticles show that with increasing the magnetic field strength during the ablation process, size of nanoparticles was decreased noticeably. This result was confirmed by SEM and TEM images. XRD pattern show that with applying external magnetic field we may have crystalline structure nanoparticles while in the absence of external magnetic field, only amorphous phase of Co nanoparticles was produced. FTIR spectra present the metal oxygen vibration at 614 and 668 cm−1, revealed octahedral and tetrahedral site of cobalt oxide system. In overall it can be concluded that external magnetic field is a strong tool to control the properties of laser ablation produced ferromagnetic nanoparticles.