Simple Chemical Co-precipitation Method Research Articles

Influence of phase transition with annealing temperature on structural, morphological, and supercapacitive characteristics of molybdenum oxide nanostructures

In this study, molybdenum oxide nanostructures (MoO3 NSs) were effectively synthesized through a simple, low-cost, surfactant-free, low-temperature, and scalable chemical co-precipitation method and investigated their synergistic effect with annealing temperature on energy storage applications for the first time. Herein, we have reported a phase transition of MoO3 NSs from hexagonal to orthorhombic after the annealing temperature varied from 100°C to 500°C at constant time. Additionally, the resultant NSs were thoroughly examined for their physio-chemical characteristics, which revealed the stable phase formation of the MoO3 NSs, respectively. Furthermore, the electroactive MoO3 NSs were pasted on Ni-foam substrate (M@NF), and electrochemical properties were evaluated using a three-electrode setup at room-air temperature in 1M KOH aqueous electrolyte across the potential range of 0V to 0.786V. As a result, the M@NF-5 electrode exhibited an impressive specific capacitance of 976.84Fg-1 at a scan rate of 1 Mv s-1, a higher energy density of 73.69Whkg-1, and a power density of 655Wkg-1 at 5mAg-1. The non-linear galvanostatic charge-discharge (GCD) profile aligns well with the cyclic voltammetry (CV) analysis. Both CV and GCD techniques confirm the pseudocapacitive behavior, with 83% capacitive retention observed after 2000 cycles. The fabricated symmetric device (M@NF-5//M@NF-5) exhibits enhanced electrochemical performance with a specific capacitance of 67.35Fg-1 at 5mAg-1 and with an energy density of 18Whkg-1, and a power density of 1750Wkg-1 at a specific current. These findings underscore the potential of chemically deposited α-MoO3 as an auspicious material for use in supercapacitor applications.

Investigation of the structural and electrical behaviour of Mn-substituted ZnO

ABSTRACT Zinc oxide (ZnO) nanostructures with the general formula Zn1-xMnxO were made using a simple and affordable wet chemical coprecipitation method. X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), and scanning electron microscopy (SEM) were used to examine the structure and morphology of the produced samples. All of the prepared oxides were found to have a single crystalline phase that is ZnO-specific and has a wurtzite structure. It is found that DC conductivity rises with temperature and a steady drop in both AC and DC conductivity with Mn concentration is seen, which might be attributed to the creation of a grain boundary defect barrier. Complex impedance analysis is used to distinguish the grain and grain boundary contribution to the system. The parameters dielectric constant (k) and dielectric loss (tan δ) decreased as the frequency increased, and as the Mn concentration increased. With increasing temperatures, the dielectric constant and loss both increased.

Engineering of Co3O4 electrode via Ni and Cu-doping for supercapacitor application.

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co3O4 nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co3O4 NPs results in a 11.5-fold increase in specific surface area (573.78m2g-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co3O4 electrode exhibits a high specific capacitance of 749Fg-1, 1.75 times greater than the pristine Co3O4 electrode's 426Fg-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co3O4 electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated.

Photocatalytic activity of Fe3O4–Fe2O3 particles supported on mordenite under visible light exposure for methylene blue degradation

Dyes pollution is a serious environmental problem and heterogeneous catalysis has been proposed as a remediation method. In this study, a set of catalysts of synthetic mordenite with iron oxides was synthesized by a simple chemical co-precipitation method assisted by subsequent thermal treatment with an oxidation process. Physicochemical characterization of prepared materials was performed by a variety of techniques, including XRD, SEM, EDS, SBET, UV–Vis DR, and XPS. Photocatalytic methylene blue (MB) degradation by the synthesized catalyst was evaluated with visible light excitation. From the studied set of catalysts, the sample prepared with a thermal treatment at 100 °C in air atmosphere for 3 h was capable of degrading ~ 90% of MB after 120 min with visible light of λ = 420 nm exposition and a small portion of H2O2 added. The catalyst used three processes to degrade MB: (1) adsorption of organic residues in the mordenite matrix support for electrostatic interactions, (2) photocatalysis heterogeneous reaction with visible light and (3) Fenton reaction catalyst with a small portion to H2O2 by Fe3O4–Fe2O3 presence. The catalytic efficiency to dye degradation was improved by a simple and economical thermal treatment without changing reaction conditions like pH, temperature, dose, or other. Studied mordenite iron oxide catalysts can be retrieved and reused at least five times without noticeable degradation, taking advantage of their magnetic properties. These catalysts could be proposed an economical, simple, and non-toxic alternative for eliminating organic dye pollution using visible light or solar irradiation in wastewater remediation related to textile, food, and pharmaceutical industries.

Synthesized Fe-doped Co3O4 nanoparticles-based anode for high-performance lithium-ion batteries application

ABSTRACT Co3O4 has been considered a promising anode material because of its high theoretical capacity (890 mAh/g) and remarkable energy density. Unfortunately, it suffers from low initial coulombic efficiency, rapid capacity fading, poor electronic conductivity, large volume changes, and aggregation during the lithium ion intercalation/deintercalation process. In this work, a series of Fe2+-doped Co3O4 nanostructured materials Co3(1-x)Fe3xO4 (x = 0, 0.01, 0.02 and 0.03) were produced by a simple chemical co-precipitation method. The Fe doping led to a slight increase of the lattice parameter, which is beneficial to the rapid diffusion of Li+ ion during the lithiation/delithiation process. Meanwhile, the Fe-doped Co3O4 sample exhibited an excellent rate capability of 886.47 mAh/g at 500 mA/g, and outstanding cyclic stability (1156.91 mAh/g for 50 cycles, with the capacity retention rate of 83.53% at the current density of 100 mA/g), demonstrating improved electrochemical performance, compared with that of pure Co3O4. The good electrochemical performance profited from the formation of oxygen vacancies by Fe doping, which provided more space for Li+ diffusion and improved the electronic conductivity of the anode material. This work provides a simple way to improve the comprehensive electrochemical performance of the transitional metal oxide Co3O4 anode electrodes for lithium-ion batteries.

β-Cyclodextrin-Functionalized Fe3O4-Supported Pd-Nanocatalyst for the Reduction of Nitroarenes in Water at Mild Conditions.

In this study, a novel heterogeneous catalyst (Fe3O4@β-CD@Pd) has been developed by the deposition of palladium nanoparticles on the β-cyclodextrin-functionalized surface of magnetic Fe3O4. The catalyst was prepared by a simple chemical co-precipitation method and characterized extensively by using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses. Herein, the applicability of the prepared material was evaluated for the catalytic reduction of environmentally toxic nitroarenes to the corresponding anilines. The catalyst Fe3O4@β-CD@Pd showed excellent efficiency for the reduction of nitroarenes in water under mild conditions. A low catalyst loading of 0.3 mol % Pd is found to be efficient for reducing nitroarenes in excellent to good (99-95%) yields along with high TON values (up to 330). Nevertheless, the catalyst was recycled and reused up to the 5th cycle of reduction of nitroarene without any loss of significant catalytic activity.

Magnetic coffee residue biosorbent for selective extraction of zinc oxide nanoparticles in water samples

ABSTRACT. Quantification of engineered nanomaterials in the environment has attracted researchers’ interest recently because of their increased release to the environment. In this study, a recyclable and easily accessible magnetized coffee residue (MCR) is proposed for magnetic solid-phase extraction (MSPE) of zinc oxide nanoparticles (ZnO-NPs) from water samples. The MCR was synthesized using a simple one-step chemical co-precipitation method from coffee residue and was characterized by state-of-the-art techniques. Various parameters affecting the MSPE efficiency of ZnO-NPs were optimized and 8.5 pH, 75 mg adsorbent, 120 min extraction time, 10 mL sample volume, 4 mL of 0.001 M HCl as an eluting solvent, and 30 min elution time were identified as the optimum conditions. Under these conditions, the method showed excellent linearity (R2 = 0.995) and good sensitivity (detection limit, 0.12 mg L-1, and quantification limit, 0.4 mg L-1). Intra and inter-day percent standard deviations were 1.4 and 2.2%, respectively, for the analysis of 6 mg L-1 ZnO-NPs. The practical applicability of the method for the extraction of ZnO-NPs in environmental samples was evaluated, and recovery values in the range of 93.0–98.2% were obtained, confirming its successful performance. Generally, the technique is easy, economical, and eco-friendly that can be considered for the extraction of metal oxide nanoparticles.
 
 KEY WORDS: Zinc oxide nanoparticles, Magnetic coffee residue, Magnetic solid-phase extraction, Flame atomic absorption spectroscopy, Environmental waters
 
 Bull. Chem. Soc. Ethiop. 2023, 37(4), 859-873. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i4.5

Maleic Anhydride-β-Cyclodextrin Functionalized Magnetic Nanoparticles for the Removal of Uranium (VI) from Wastewater

New maleic anhydride-β-cyclodextrin functionalized magnetic iron oxide nanoparticles (IONPs@MAH-β-CD) were prepared through the simple chemical coprecipitation method. Macroscopic batch experiments were carried out to study its absorption behavior for uranium (VI) under different environmental conditions. Using the magnetic separation technique, it was possible to easily separate IONPs@MAH-β-CD from uranium-containing wastewater. The equilibrium for uranium (VI) adsorption was reached for 180 min. The results showed that the kinetics and isotherm of the adsorption process were consistent with the pseudo-second-order kinetic model and Langmuir model, respectively, indicating that it was a chemisorption process. Compared with pure IONPs, the maximum adsorption quantity of maleic anhydride-β-cyclodextrin-coated iron oxide nanoparticles for uranium (VI) was significantly improved, which could reach 163.93 mg g−1. The recyclability of the IONPs@MAH-β-CD was investigated, and FTIR and XPS characterization were used to explore the possible mechanism of U(VI) adsorption.

Physical property modifications with transition metal doping in nanostructured Zn1-xNixO (x = 0.03, 0.05); synthesized by chemical co-precipitation technique

Present work demonstrate the structural and optical property study of Zn1-xNixO (x= 0.03, 0.05) nanoparticles (NPs). These samples have been prepared by simple chemical co-precipitation method. Finally these samples are annealed at 500°C for 3 hours. Structural characterization has been performed by doing X-Ray diffraction (XRD) at room temperature. The XRD patterns confirm the hexagonal wurzite structure for these samples. We have estimated the lattice parameters (a & c) and determine the c/a ratio of respective samples after structural analysis. Morphology of these nanoparticles has been investigated by performing SEM. In addition UV-visible and Photoluminescence (PL) study has been performed. PL emission spectra show a broad UV emission peak. Doping at the Zn-site by Ni ions could induce inter-band levels within the band gap. Transition between those levels may responsible for broadening of the UV peak. In addition defect mediated visible emission has also been observed in the PL study. Further to investigate the effect of doping on microstructure, Raman spectra of Zn1-xNixO samples are taken. Wurzite ZnO belongs to space group: C4 6v and consequently six first order phonon modes are expected to appear in the Raman spectra. Raman scattering has been analysed according to the existing literature and details of analysis are presented in this work.

Dihydrocaffeic Acid-Decorated Iron Oxide Nanomaterials Effectively Inhibit Human Calcitonin Aggregation.

To date, more than 30 human peptides or proteins have been found to form amyloid fibrils, most of which are associated with human diseases. However, currently, no cure for amyloidosis exists. Therefore, development of therapeutic strategies to inhibit amyloid formation is urgently required. Although the role of some amyloidogenic proteins has not been identified in certain diseases, their self-assembling behavior largely affects their bioactivity. Human calcitonin (hCT) is a hormone peptide containing 32 amino acids and is secreted by the parafollicular cells of the thyroid gland in the human body. It can regulate the concentration of calcium ions in the blood and block the activity of osteoclasts. Therefore, calcitonin has also been considered a therapeutic peptide. However, the aggregation of hCT hinders this process, and hCT has been replaced by salmon calcitonin in drug formulations. Recently, iron oxide nanomaterials have been developed as potential materials for various applications owing to their high biocompatibility, low toxicity, and ease of functionalization. In this study, nanoparticles (NPs) were prepared using a simple chemical coprecipitation method. We first demonstrated that dopamine-conjugated Fe3O4 inhibited hCT aggregation, similar to what we found when carbon dots were used as core materials in the previous study. Later, we continued to simplify the preparation process, that is, the mixing of dihydrocaffeic acid (DCA) and iron oxide NPs, to maintain their stability and inhibitory effect against hCT aggregation. Furthermore, DCA-decorated Fe3O4 can dissociate preformed hCT amyloid fibrils. This appears to be one of the most promising ways to stabilize hCT in solution and may be helpful for amyloidosis treatment.

Ag2O modified CuO nanosheets as efficient difunctional water oxidation catalysts

Semiconductors have been given immense attention for years regarding the use of photocatalytic water oxidation reaction (WOR) to reduce the potential barrier. However, some known semiconductors, such as TiO2 and CuO, exhibit outstanding water oxidation activity in the UV light region. Therefore, it is important to explore the methods to expand the usage of these catalysts in the visible as well as IR regions. This study introduces a simple and facile chemical co-precipitation method to fabricate a sort of Ag2O-modified CuO nanosheets with excellent catalytic properties. The as-prepared Ag2O/CuO nanosheets exhibit a robust catalytic efficiency towards the visible-light-driven WOR. Due to the addition of Ag2O, the Ag2O/CuO nanosheets display photocatalytic activity. The total turnover number (TON) was 8.20 and when the effect of chemocatalytic activities was deducted, the TON, quantum yield (QY), and corresponding photonic efficiency (ζp) are 2.92, 0.65 %, and 0.33 %, respectively, which shows that Ag2O/CuO nanosheets possess water oxidation sites as well as light-absorption centers. With the synergy effect between the Ag2O and CuO, the catalyst efficiently reduced the recombination probability of photoexcited electrons and holes. Intriguingly, Ag2O/CuO nanosheets expanded the utility in the visible region as long as 765 nm, which evolved 95.89 % oxygen compared to that of the light cutting off at 420 nm. The insight into the WOR pathway is that surficial –OH groups of Ag2O/CuO nanosheets play a key role in this catalytic reaction. The mechanism of Ag2O/CuO nanosheets in the persulfate/NaOH system for water oxidation was consequently proposed according to electron spin resonance measurements and two radical scavengers (methanol and tert-butanol alcohol). This study offers useful guidance for developing difunctional water oxidation catalysts without photosensitizers.

Room Temperature Ferromagnetism In Chemically Synthesized Zno Nanoparticles

Zinc Oxide (ZnO) is an intrinsic n-type metal oxide-based semiconductor with a wide bandgap and has attracted much attention of researchers due to its unique properties and applications in optoelectronic devices, ceramics, catalysis, pigments and many others. Herein, ZnO nanoparticles (NPs) have been successfully synthesised by a simple and cost-effective chemical co-precipitation method. The product is characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis absorption spectroscopy (UV-Vis), photoluminescence spectroscopy (PL) and vibrating sample magnetometer (VSM). The XRD pattern confirms the formation of the wurtzite phase ZnO nanoparticles. The structural information and composition were further confirmed by FTIR where the stretching vibration bands appeared at 493 cm–1, 562 cm–1 and 831 cm–1 are due to the Zn-O bond. The absorption edge is observed at 359 -nm which is due to its quantum confinement effect whereas the PL emission is observed in the range of 370 nm-600 nm. M-H loop shows the presence of room temperature ferromagnetism in ZnO nanoparticles possibly due to the presence of oxygen vacancies.

Iron/titanium oxide-biochar (Fe2TiO5/BC): A versatile adsorbent/photocatalyst for aqueous Cr(VI), Pb2+, F- and methylene blue

This is the first report of the metal Fe-Ti oxide/biochar (Fe2TiO5/BC) composite for simultaneous removal of aqueous Pb2+, Cr6+, F- and methylene blue (MB). Primary Fe2TiO5 nano particles and aggregates were dispersed on a high surface area Douglas fir BC (∼700 m2/g) by a simple chemical co-precipitation method using FeCl3 and TiO(acac)2 salts treated by base and heated to 80 °C. This was followed by calcination at 500 °C. This method previously was used without BC to make the neat mixed oxide Fe2TiO5, exhibiting a lower energy band gap than TiO2. Adsorption of Cr(VI), Pb(II), fluoride, and MB on Fe2TiO5/BC was studied as a function of pH, equilibrium time, initial adsorbate concentration, and temperature. Adsorption isotherm studies were conducted at 5, 25, and 45 ℃ and kinetics for all four adsorbates followed the pseudo second order model. Maximum Langmuir adsorption capacities for Pb2+, Cr6+, F- and MB at their initial pH values were 141 (pH 2), 200 (pH 5), 36 (pH 6) and 229 (pH 6) mg/g at 45 ℃ and 114, 180, 26 and 210 mg/g at 25 ℃, respectively. MB was removed from the water on Fe2TiO5/BC by synergistic adsorption and photocatalytic degradation at pH 3 and 6 under UV (365 nm) light irradiation. Cr6+, Pb2+, F-, and MB each exhibited excellent removal capacities in the presence of eight different competitive ions in simulated water samples. The removal mechanisms on Fe2TiO5/BC and various competitive ion interactions were proposed. Some iron ion leaching at pH 3 catalyzed Photo-Fenton destruction of MB. Fe2TiO5, BC, and Fe2TiO5/BC bandgaps were studied to help understand photocatalysis of MB and to advance supported metal oxide photodegradation using smaller energy band gaps than the larger bandgap of TiO2 for water treatment. A long range goal is to photocatalytically destroy some sorbates with adsorbents to avoid the need for regeneration steps.

Structural Characterization of CaF2: Dy Nanoparticles Synthesized by Simple Chemical Co-Precipitation Method

In this work, nanoparticles of dysprosium doped calcium fluoride (CaF2:Dy) has been prepared by Simple Chemical Co-Precipitation Method in which 0.05 mol of CaCL2 is used as the calcium ion source and 0.05 mol of NH4F as the fluoride ion source. 1 mol% of Dy2O3was used as the dopant. The synthesized nanoparticle samples was characterized by X- ray diffraction (XRD) and the crystallite size using the dominant (111) peak was found to be 56.09 nm. SEM image shows the presence of spherical shaped nanoparticles. The PL emissions bands are observed at 479 nm (blue emission peak) and 573 nm (yellow emission peak).

CuO/NiO bimetallic nanocomposite: A facile DNA assisted synthetic approach and evaluation of bio efficacy

In this present work, a simple chemical co-precipitation method was used to synthesize deoxyribonucleic acid (DNA) capped CuO-NiO bimetallic nanocomposite. The morphology and structure related properties of the samples were analyzed using Energy Dispersive X-Ray Analysis, X-Ray Diffraction, Transmission Electron Microscopy and Scanning Electron Microscopy. Widely used Agar well diffusion method evaluated the antimicrobial activity of the sample. DPPH and FRAP assays were applied to test the antioxidant activity of the sample. Average crystallite size of 16.218 nm NiO and 15.871 nm CuO were confirmed within CuO- NiO bimetallic oxide nanoparticles by means of XRD technique. EDAX studies confirmed the purity of the sample. The grain size obtained from TEM studies matches with the XRD results. The free radical scavenging activity of sample was higher in lower concentrations, viz. 0.1, 1, 5 and 10 µg/ml of the sample and activity decreased after that. The IC50 value in FRAP assay shows the potential of this mixed metal oxide nanoparticle in radical scavenging. In agar well cut method, the sample showed moderate antibacterial activity against Mycobacterium smegmatis and Salmonella typhimurium. The results also showed that the CuO-NiO bimetallic nanoparticles are biologically compatible, environmentally benign and economical material having potential applications in biomedical industry.

Specific Absorption Rate Dependency on the Co2+ Distribution and Magnetic Properties in CoxMn1-xFe2O4 Nanoparticles.

Mixed ferrite nanoparticles with compositions CoxMn1-xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were synthesized by a simple chemical co-precipitation method. The structure and morphology of the nanoparticles were obtained by X-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, and Mössbauer spectroscopy. The average crystallite sizes decreased with increasing x, starting with 34.9 ± 0.6 nm for MnFe2O4 (x = 0) and ending with 15.0 ± 0.3 nm for CoFe2O4 (x = 1.0). TEM images show an edge morphology with the majority of the particles having cubic geometry and wide size distributions. The mixed ferrite and CoFe2O4 nanoparticles have an inverse spinel structure indicated by the splitting of A1g peak at around 620 cm−1 in Raman spectra. The intensity ratios of the A1g(1) and A1g(2) peaks indicate significant redistribution of Co2+ and Fe3+ cations among tetrahedral and octahedral sites in the mixed ferrite nanoparticles. Magnetic hysterics loops show that all the particles possess significant remnant magnetization and coercivity at room temperature. The mass-normalized saturation magnetization is highest for the composition with x = 0.8 (67.63 emu/g), while CoFe2O4 has a value of 65.19 emu/g. The nanoparticles were PEG (poly ethylene glycol) coated and examined for the magneto thermic heating ability using alternating magnetic field. Heating profiles with frequencies of 333.45, 349.20, 390.15, 491.10, 634.45, and 765.95 kHz and 200, 250, 300, and 350 G field amplitudes were obtained. The composition with x = 0.2 (Co0.2Mn0.8Fe2O4) with saturation magnetization 57.41 emu/g shows the highest specific absorption rate (SAR) value of 190.61 W/g for 10 mg/mL water dispersions at a frequency of 765.95 kHz and 350 G field strength. The SAR values for the mixed ferrite and CoFe2O4 nanoparticles increase with increasing concentration of particle dispersions, whereas for MnFe2O4, nanoparticles decrease with increasing the concentration of particle dispersions. SARs obtained for Co0.2Mn0.8Fe2O4 and CoFe2O4 nanoparticles fixed in agar ferrogel dispersions at frequency of 765.95 kHz and 350 G field strength are 140.35 and 67.60 W/g, respectively. This study shows the importance of optimizing the occupancy of Co2+ among tetrahedral and octahedral sites of the spinel system, concentration of the magnetic nanoparticle dispersions, and viscosity of the surrounding medium on the magnetic properties and heating efficiencies.

Synthesis of YVO4:Eu3+ nanophosphors by the chemical coprecipitation method at room temperature

YVO4:Eu3+ phosphors have been subject of studies in recent years because of their intense luminescence, their various applications in lighting devices and, recently, because of their potential use in biological probes resulting from their low toxicity. Achieving YVO4:Eu3+ nanophosphors with size less than 20 nm has been a difficult task due to the annealing treatments used during their synthesis. In this work we synthesized nanophosphors with average crystallite sizes up to 6 nm by a simple chemical coprecipitation method at room temperature without subsequent annealing treatment. Using Rietveld refinement, the formation of Y1-xEuxVO4 solid solutions, where Eu3+ occupies the positions of Y3+ in the host crystal, is verified. Emission lines from activator depend on the synthesis method used and the local environment of Eu3+ which is different in bulk phosphors and nanophosphors; furthermore, decay time is shorter for bulk phosphors and not for nanophosphors as might be expected. The crystallite size achieved, the simplicity of the synthesis method and the identified luminescent properties offer a range of new applications for synthesized nanophosphors.

Graphene oxide (rGO)-metal oxide (TiO2/Ag2O) based nanocomposites for the removal of rhodamine B at UV–visible light

The nanosheet flower-shaped rGO-Ag2O/TiO2 (rAT) ternary composite material was prepared by two-step hydrothermal and one-step wet chemical co-precipitation methods. In the first step, anatase titanium dioxide (TiO2) with a nano-flaky flower-like structure was prepared by a hydrothermal method. In the second step, the graphene-coated TiO2 structure was prepared by the hydrothermal method to form rGO-TiO2 (rT) composite material. In the third step, a simple wet chemical co-precipitation method was used to prepare the graphene-coated Ag2O/TiO2 (AT) nanostructure to form an rAT ternary composite material. The rAT was placed under UV–visible light to degrade Rhodamine B (RhB) solution. It is concluded that within 70 min, the degradation rate of the 10 mg rAT ternary composite material is as high as 92.3%. The result showed that the rAT had an excellent photocatalytic performance. The main reason was that the three materials of rGO, Ag2O, and TiO2 had particularities in morphology, structure, and performance. TiO2 had a layered flake flower-like structure, Ag2O had the characteristics of the narrow bandgap and excellent dispersion, and rGO had a unique two-dimensional network structure. It was further found that in terms of design ideas and preparation methods, the rAT ternary composite photocatalyst will provide a new vision and brilliant prospect for photocatalytic materials.

TUNING OF CRYSTALLITE SIZE, ENERGY GAP, AND MAGNETIC PROPERTY OF Mn-DOPED CoFe2O4 NANOPARTICLES

This paper focuses on the synthesis and structural, optical, and magnetic characterization of Mn-doped CoFe2O4 nanoparticles synthesized by a simple chemical co-precipitation method. Synthesized magnetic nanoparticles were characterized by XRD, FTIR, UV-Vis, PL, TEM, VSM, and EPR spectroscopy. XRD analysis confirmed the significant reduction in the crystallite size from [Formula: see text][Formula: see text]nm to 10[Formula: see text]nm as the Mn content is increased from 0 to 1. UV-Vis spectra confirmed that the Co–Mn ferrite is a direct bandgap magnetic material that possesses an energy gap from 3.92[Formula: see text]eV to 4.33[Formula: see text]eV. FTIR vibrational frequency observed between 468 and 548 [Formula: see text]confirmed the existence of metal–oxygen bond at tetrahedral and octahedral sites. Photoluminescence spectra confirmed the red emission of the samples from the peak at 680[Formula: see text]nm. TEM analysis suggests that the single domain of CoFe2O4 nanoparticles may vary between 38 and 72[Formula: see text]nm. Composition analysis confirmed the homogeneous mixing of Co, Mn Fe, and O atoms in the synthesized samples. The VSM study confirmed that Mn substitution favors transition from ferromagnetic to superparamagnetic. VSM analysis also confirmed the lessening in saturation magnetization and coercivity on Mn doping. The X-band electron paramagnetic resonance spectrum recorded at room temperature conveys that the superexchange interaction is increased with the increase in Mn concentration.

Synthesis of Zinc-Copper-Iron(II, III) Oxide Nanocomposites and their Photocatalytic Efficiency for Crystal Violet Degradation

The synthesis, characterization, and application of metal oxide nanocomposites have received increasing interest in the field of nanoscience and technology with several possible opportunities. Nanocomposites containing two or more dissimilar band gaps semiconductors provide exceptional properties to photocatalysts. A simple chemical co-precipitation method was employed to synthesize ZnO:CuO:Fe2O3 mixed metal oxide nanocomposites followed by calcination at 5000C. The prepared nanocomposites were characterized by XRD, FTIR, SEM, and TEM. The FTIR and XRD spectra confirmed the characteristic vibrations of ferrite atoms along with Cu-O and Zn-O vibrations. The crystallite particle size calculated by Debye Scherrer formula matched the size obtained by SEM and TEM images. The photocatalytic efficiency of the ZnO:CuO:Fe2O3 nanocomposites was assessed using crystal violet dye in the presence of sunlight. Variation in the concentration of Cu with respect to zinc in the nanocomposites enhanced photodegradation efficiency in this investigation. Our results indicated that the variation in the composition of ternary nanocomposite catalysts influence the competence for dye removal from waste water.