Facile Chemical Co-precipitation Method Research Articles

Comparison of the lithium storage performance and electrochromic behavior of Prussian blue and its analogues

Nanosized Prussian blue (FeHCF), cobalt hexacyanoferrate (CoHCF), nickel hexacyanoferrate (NiHCF), copper hexacyanoferrate (CuHCF), and zinc hexacyanoferrate (ZnHCF) particles are prepared by facile chemical co-precipitation method. The microstructure of the samples is characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and N2adsorption measurements. The lithium storage behavior and electrochromic performance of the five samples are systematically studied and compared. Among them, FeHCF presents two pairs of distinct charge/discharge plateaus; the other four samples exhibit one pair of charge/discharge plateaus, and plateau potential varies with the change of metal centers. During discharge and charge processes, the color of FeHCF can be reversibly switched in three colors (blue ↔ white ↔ green); while the CoHCF, NiHCF, CuHCF, and ZnHCF can be reversibly switched in two different colors corresponding to green ↔ red, yellow ↔ colorless, yellow brown ↔ dark red, and light yellow ↔ colorless, respectively. The results reported in this work could be helpful for rational design and performance regulation of Prussian blue analogues as electrochemical energy storage and electrochromic bifunctional materials.

Facile fabrication of MgAl2O4/MWCNT nanocomposite for efficient and stable solar-driven degradation of organic dye

This work reports the synthesis and characterization of Magnesium Aluminate (MgAl2O4) and Magnesium Aluminate/Multi Walled Carbon Nanotube (MgAl2O4/MWCNT) nanocomposite by facile chemical co-precipitation method for the dye degradation application. MgAl2O4 and MgAl2O4/MWCNT nanocomposite are characterized by Scanning Electron Microscopy (SEM), x-ray Diffractometry (XRD), Raman Spectrometry, UV–vis Spectrophotometry (UV–vis), Fourier Transform Infrared Spectroscopy(FTIR), and x-ray Photoelectron Spectroscopy (XPS). Surface morphology of MgAl2O4/MWCNT nanocomposite exhibits entangled needle-like structures while MgAl2O4 spinel comprises agglomerated nanoparticles of different sizes. XRD confirms the formation of MgAl2O4. XPS identifies the chemical states and binding energies of constituent elements present in the sample. Optical properties reveal that addition of MWCNTs in MgAl2O4 decreases the optical bandgap energy from 3.02 eV to 2.78 eV. MgAl2O4/MWCNT nanocomposite shows reduced bandgap compared to pristine MgAl2O4 due to increased chemical defects or vacancies in intergranular regions and chemical interaction between MgAl2O4 and MWCNT, leading to the formation of new energy levels in MgAl2O4/MWCNT nanocomposite. Addition of MWCNTs provides a large surface area, more active sites, and enhances electron mobility between energy levels. MgAl2O4/MWCNT nanocomposite proves itself a better photocatalyst due to the fast degradation of Methyl Blue (MB) in 65 min as compared to MgAl2O4 which degrades the dye in 90 min. MgAl2O4/MWCNT nanocomposite also shows good stability and reusability even after performing the six cycles of dye degradation.

Evaluation of structural parameters of monoclinic nanocrystalline CuO and study of sunlight-driven photocatalytic dye degradation, antimicrobial and antioxidant potential

Highly pure, crystalline and spherical-shaped Copper oxide nanoparticles (NPs) have been synthesized via facile chemical coprecipitation. Various models including the Scherrer, Monshi-Scherrer, Williamson-Hall, Size-Strain Plot and Halder-Wagner method have been applied to study the crystal structure characteristics. The lattice parameters associated with the monoclinic crystal lattice of CuO NPs were estimated to be a = 4.69 Å, b = 3.41 Å, c = 5.14 Å and β = 99.87(degree), unit cell volume V = 81.35Å3 and cell density dx = 6.49 g/cm3. The photocatalytic dye degradation proficiency at 20 mg/l CuO concentration and 120 min sunlight exposure results the order of percentage dye degradation Malachite Green (88.4%) > Crystal Violet (70.8%) > Eosin Yellow (70.2%) > Methylene Blue (54.08%) dyes. The antimicrobial activity assessment was done against the broad-spectrum pathogenic microbes unveiled the exceptional microbial controlling capability of CuO NPs. Furthermore, the antioxidant activity test demonstrated the potential free radical scavenging activity of CuO NPs with an IC50 value of 47.733 µg/ml. Highlights Synthesis of pure and spherical shaped nanocrystalline CuO was done by using low cost and facile chemical coprecipitation method. XRD, FTIR, FESEM, EDX, UV-Vis, and Raman spectroscopic techniques were used for characterization purpose. The structural and crystallographic parameters of monoclinic crystal structure of CuO NPs were evaluated successfully. The photocatalytic performance of CuO NPs follow the percentage dye degradation order as MG (88.4%) > CV (70.8%) > EY (70.20%) > MB (54.08%) after 120 minutes of sunlight exposure. CuO NPs exhibit promising antifungal activity against COVID-19 associated Pulmonary Aspergillosis (CAPA) causing pathogenic fung. CuO NPs show potential DPPH free radical scavenging activity with an IC50 value of 47.733 µg/ml.

Defects assisted the enhancement of optical and ferromagnetism in Zn1-xCoxS quantum dots: Toward efficient optoelectronic and spintronic applications

Colloidal Co-doped ZnS Quantum dots (QDs) were successfully synthesized through a facile and effective chemical co-precipitation method using polyethylene glycol (PEG) as a capping agent. A comprehensive study on the structure, optoelectronic, and magnetic properties of ZnS: Co2+ QDs was thoroughly carried out using diverse characterization techniques. Transmission electron micrographs reveal spherical QDs with a mean particle size of 5 ± 0.5 nm, whereas the X-ray diffraction (XRD) analysis and Raman spectroscopy confirm the exclusive presence of cubic ZnS phase structure, without any signs of Co-related impurity phases. Energy-dispersive x-ray (EDX) analysis verifies the presence of only three elements: Zinc, Cobalt, and Sulphur, with nearly stoichiometric proportions. X-ray photoemission (XPS) analysis confirmed the presence of Co2+ ions in the divalent oxidation state as well as the fair existence of sulphur vacancies. Optical measurements demonstrate that Co-doping in ZnS leads to a decrease in the optical band gap owing to the presence of defects that create localized states within the band structure. In addition, the refractive index (n) is found to increase with Co-doping level due to the increase in the polarizability. The outcomes of optical properties reveal that the tunability of the optical band gap and dispersive oscillator parameters in Co-doped ZnS QDs results in an enhancement of the non-linear optical parameters, such as third-order non-linear optical susceptibility χ(3), and non-linear refractive index n2, rendering them well-suited for applications in optoelectronic devices. Furthermore, the room-temperature photoluminescence (PL) spectra revealed that the Co-doped ZnS QDs have two broad emission bands, including the blue emission, and the green emission. By varying the level of Co-doping, it becomes possible to effectively control the relative PL intensities of dual-color emissions, highlighting their potential for producing adjustable color outputs. The room temperature ferromagnetic behaviour of the QDs has been observed and analyzed in accordance with the bound magnetic polarons model. These findings suggest that Co-doped ZnS QDs can be utilized effectively in the design of spintronic devices.

Rapid catalytic reduction of environmentally toxic azo dye pollutant by Prussian blue analogue nanocatalyst.

The release of toxic azo dyes pollutants in the environment from different industries represents a public health concern and a serious environmental problem. Therefore, the conversion of hazardous methyl orange (MO) azo dye to environmentally benign products is a critical demand. In this work, an eco-friendly Prussian blue analogue (PBA) was synthesized and its catalytic activity toward the reduction of MO was investigated. The PBA copper(ii) hexacyanocobaltate(III) (Cu3[Co(CN)6]2) was synthesized by a facile inexpensive chemical coprecipitation method without using hazardous solvents. The nanocatalyst was characterized using XPS, Raman, FTIR spectroscopy, and XRD. The chemical reduction of MO using NaBH4 and the PBA as nanocatalyst was monitored by UV-VIS spectroscopy. Toxic MO was completely reduced in 105 s with a rate constant (k) 0.0386 s-1 using only 10 μg of the PBA nanocatalyst. Besides the powerful catalytic activity, the nanocatalyst also showed excellent stability and recyclability for ten consecutive cycles, with no significant decrease in the catalytic performance. Therefore, the proposed PBA is a promising, stable, cost-effective, and eco-friendly nanocatalyst for the rapid elimination of hazardous azo dyes.

Enhanced electrochemical performance of CuO/NiO/rGO for oxygen evolution reaction

To design the highly active, stable electrocatalyst for oxygen evolution is emerging as challenging task for sustainable energy production. Herein, we fabricated the non-noble CuO/NiO/rGO nanocomposite approached by facile chemical co-precipitation method. The successful formation of binary metal oxide nanocomposite with reduced graphene oxide was confirmed with monoclinic CuO and cubic NiO, which is clearly revealed in the XRD diffraction results. By incorporating the CuO and NiO into the rGO sheets results homogeneous tiny nanoparticles morphology decorated on the graphene sheets which improving interaction among metal nanoparticles and carbon based products. The electrocatalytic performance of resultant binary metal oxide nanocomposite with rGO was investigated in alkaline KOH environment towards oxygen evolution reaction. The 200 mV overpotential was attained at 10 mA/cm2 with smaller 165 mV/dec Tafel value. The elevated electrochemical surface area (ECSA) value of 132.5 cm2 was estimated from cyclic voltammetry analysis of optimized CuO/NiO/rGO electrocatalyst. The electrochemical impedance spectrum of the prepared electrocatalyst shows that the low 0.04 Ω charge transfer resistance is highly desirable to the better conductivity. The prepared CuO/NiO/rGO electrocatalyst stability was verified by chronoamperometry test at low 10 mA/cm2 and exhibited stable performance up to 16 h towards OER. Hence, this work contributes innovative synergistic approach for growth of cost effective binary metal-oxide (CuO/NiO) nanocomposite combined with conductive carbon material for oxygen evolution reaction.

Spongy magnetic hydroxyapatite for the enhanced Pb2+ removal and its dynamic sorption mechanism

Nano-magnetic hydroxyapatite (Fe3O4/nHAP) has superior properties for the removal of lead (Pb) from aqueous solutions. In this study, we synthesized several spongy Fe3O4/nHAP composite materials using the facile chemical co-precipitation method with the assist of ultrasound. Appropriate Fe3O4 addition increased the specific surface area of Fe3O4/nHAP with a porous structure, contributing to the more sorption sites exposure to lead ions (Pb2+) for fast kinetic and larger sorption capacity of 1500 mg g-1. The characteristic results manifest that complexation and dissolution-precipitation were the two main sorption mechanisms. Through the Pb/Ca molar ratio, solution pH, Pb fraction changes and the additional XRD results, the main sorption mechanisms turned from complexation to dissolution-precipitation and the adsorbed-Pb transformed from unstable Pb-complexes to stable Pb-phosphate during the removal process. Complexation effect dominated the Pb2+ removal in higher Pb2+ concentration solutions while dissolution-precipitation controlled in low Pb2+ concentration solutions. Pb5(PO4)3(OH) was the main product in the solutions of pH ranging from 2.76 to 5.25, and PbHPO4 precipitates was formed when the pH was lower than 2.76. Regeneration experiment and fraction analysis demonstrated the stability of Fe3O4/nHAP after Pb2+ sorption and desorption. Our findings provide a facile preparation method of Fe3O4/nHAP with their specific properties for the Pb2+ removal from aqueous solutions. Comprehensive mechanisms for the affinity of Pb2+ and Fe3O4/nHAP can propose strategies in the further removal or stabilization of heavy metals in practical environmental remediation.

Multiferroics Made via Chemical Co-Precipitation That Is Synthesized and Characterized as Bi(1−x)CdxFeO3

Cd-doped BiFeO3 powders, with varying doping concentrations of Cd (Bi(1−x)CdxFeO3, where x = 0–0.3), were prepared through a facile chemical co-precipitation method and calcinated at 550 °C in the air. The BiFeO3 has a rhombohedral crystal structure, which changes to an orthorhombic crystal structure with an increase in Cd doping. The presence of dopant has also altered the bandgap of material suppressing it from 2.95 eV to 2.51 eV, improving the visible light absorption. Vibrating sample magnetometry (VSM) confirmed stronger ferromagnetic character for Bi0.7Cd0.3FeO3 with a coercivity of 250 Oe, and remnant magnetization was 0.15 emu/g, which is because of the misalignment of the two sublattices of perovskite structure after doping resulting in the imbalanced magnetic moment giving rise to net nonzero magnetic behavior. The particle size reduction is observed with an increase in the doping concentration of Cd.

Chemically synthesized manganese oxide nanorods for effectual organic dye removal and energy storage application

Manganese oxide nanoparticles (MnO2) are successfully synthesized by using a facile chemical co-precipitation and reflux-assisted co-precipitation method with varying annealing temperatures and reflux time respectively. The synthesized samples' structural, optical and thermal properties are investigated by XRD, FTIR spectra, Ultraviolet–Visible spectroscopy, Thermogravimetric Analysis and BET surface area analyzer. The average crystallite sizes assessed by Scherrer's equation (Williamson- Hall plot) of prepared samples are in the range of 6–8 nm (6–7 nm) for the reflux-assisted method and 15–30 nm (20–46 nm) for the co-precipitation method respectively. The presence of peaks associated with Mn-O bonds in FTIR spectra confirmed the formation of MnO2 nanoparticles. FESEM studies revealed the nanorod-type morphologies of samples. The prepared samples showed pseudocapacitive behaviour and significant photocatalytic degradation of brilliant green dye.

Amorphous nickel tungstate nanocatalyst boosts urea electrooxidation

Urea oxidation reaction (UOR) is an important reaction for achieving a sustainable and clean energy conversion. The reaction rates of UOR on the commonly used Ni-based electrocatalysts, however, are still limited. In this study, an amorphous NiWO4 nanomaterial synthesized via a facile chemical co-precipitation method is developed as a novel and efficient catalyst for UOR. Impressively, the maximum current density of the prepared amorphous NiWO4 is almost two orders of magnitude higher than that of the crystalline counterpart. The superior activity is attributed to not only the enrichment of electrochemically active sites, but also the more suitable binding energies toward urea reactant and CO2 product on the amorphous NiWO4 as revealed by in situ infrared spectroscopy and theoretical calculations. This work opens up new insights into the development of cost-effective catalysts as well as indicates catalyst phase engineering as a promising strategy for enhancing the UOR performance.

Controlled Synthesis of Europium-Doped SnS Quantum Dots for Ultra-Fast Degradation of Selective Industrial Dyes

Herein, SnS and Eu-doped SnS QDs have been synthesized by a facile chemical co-precipitation method for efficient photocatalytic degradation of organic dye molecules. The structural, morphological, and optical properties of QDs were investigated by various physiochemical characterization techniques. The photocatalytic degradation of methylene blue (MB) and crystal violet (CV) dyes have been studied under visible light irradiation under direct sunlight using a spectrophotometer. Enhanced photodegradation efficiency of 87% and 94% were attained for SnS and Eu (4%)-doped SnS, respectively. For CV dye, the pure SnS showed only 70.7% however the Eu (4%)-doped SnS achieved 99% efficiency. The rate constant value of the doped SnS was found to be much higher than that of pure SnS for both dyes. The obtained results from various characterization studies provided the reason for the enhancement of the photocatalytic activity of Eu-doped SnS QDs due to the presence of Eu3+ in the SnS lattice, and also smaller crystallite size with high surface area and its morphological features. Moreover, the Eu3+ plays an essential role in reducing the band gap, hampering recombination, and the generation of free radicals, thus the QDs promoted attractive degradation activity and high stability.

Carbonate doped nickel-cobalt layered double hydroxide for high performance asymmetric supercapacitors

In this work, a facile chemical co-precipitation method to prepare nickel-cobalt layered double hydroxide (Ni, Co-LDH) is reported. Through the addition of NaHCO 3 , carbonate ions (CO 3 2- ) are introduced into the LDH in a controlled way. The doping of CO 3 2- causes the original nanosheet structure to bend and interconnect, which increases the contact area between the electrode and the electrolyte, enhancing the energy storage characteristics of materials. Appropriate CO 3 2- doping effectively increases the specific capacity of Ni, Co-LDH. When the doping ratio of carbonate is 5% (Ni, Co-LDH/CO 3 -5%), the specific capacity is improved from 1432 F g -1 (undoped) to 1970 F g -1 at 1 A g -1 . Furthermore, the electrode exhibits satisfactory rate capability, retaining 82.8% of the specific capacity at 20 A g -1 . Moreover, an asymmetric supercapacitor (ASC), assembled with Ni, Co-LDH/CO 3 -5% as the positive electrode and activated carbon as the negative electrode, possesses a high energy density of 54.8 Wh kg -1 at a power density of 374.9 W kg -1 and remains 80.8% after 10000 cycles at 10 A g -1 , demonstrating excellent cyclic stability. The doping of CO 3 2- causes the original nanosheet structure to bend and interconnect, which increase the contact area between the electrode and the electrolyte, enhancing the energy storage characteristics of materials. An asymmetric supercapacitor, assembled with Ni, Co-LDH/CO 3 -5% as the positive electrode and activated carbon as the negative electrode, possesses a high energy density of 54.8 Wh kg-1 at a power density of 374.9 W kg -1 , 80.8% of the initial capacitance after 10000 cycles at 10 A/g. • Ni, Co-LDH/CO 3 - x were prepared by co-precipitation method. • The Ni, Co-LDH/CO 3 -5% exhibits specific capacity of 1970 F g -1 . • The ASC shows a high energy density of 54.8 Wh kg -1 .

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.

Facile synthesis of MgO nanoparticles for effective degradation of organic dyes.

In the present study, we have synthesized magnesium oxide (MgO) nanoparticles by a facile and cost-effective chemical co-precipitation method with annealing at three different temperatures (350°C, 450°C, and 550°C) for the removal of various organic dyes. X-ray diffraction studies revealed that the prepared samples are having sizes below 20 nm and with pure phase. Phase transformation of hexagonal Mg(OH)2 nanoparticles to discretely cubical structured MgO nanoparticles has been observed with increasing the annealing temperatures which is also supported by the TGA/DSC analysis. Mg-O stretching vibration peaks in the range of 400-800 cm-1 obtained by FTIR spectroscopy support the formation of MgO nanoparticles. The observed Raman active bands for the annealed sample at 550°C confirm the formation of the nanocrystalline phase since these bands are typically absent in the bulk MgO as well as in Mg(OH)2. The surface morphology of the as-prepared Mg(OH)2 are aggregated nano-petals which changed into spherical shape for MgO annealed at 550°C as studied by field emission scanning electron microscopy (FESEM). The specific surface area of MgO nanoparticles annealed at 550°C using BET isotherms is found to be 37.487 m2g-1. The optical bandgaps of the prepared samples are found to be in the range of 4.4 to 5.1 eV using the Tauc plot. Adsorption studies with a variation of initial brilliant green dye concentration and contact time are carried out along with the studies of adsorption kinetic and isotherm models. Langmuir isotherm model is the most suitable model on the basis of correlation constant with maximum BG dye adsorption capacity onto MgO@550°C which is found to be 63.9 mg/g. The adsorption kinetics followed the pseudo-second-order model. Also prepared pristine MgO nanoparticles showed significant photocatalytic performance for the degradation of various dyes; brilliant green (BG: 88.91%), methylene blue (MB: 79.05%), crystal violet (CV: 76.49%), methyl orange (MO: 68.62%), and brilliant blue (BB: 40.44%) under visible irradiation. MgO nanoparticles could be a promising adsorbent and photocatalyst that may be employed in the treatment of effluents from industries.

N-doped residual carbon from coal gasification fine slag decorated with Fe3O4 nanoparticles for electromagnetic wave absorption

• Fe 3 O 4 @N-doped residual carbon composites were successfully fabricated. • The effective absorption bandwidth reached 4.16 GHz at 1.5 mm thickness. • Strong absorption, broad bandwidth and thin thickness were simultaneously achieved. • The reasons for high-performance microwave absorption are studied. The electromagnetic wave absorption (EMWA) performance of materials is affected by their dielectric and magnetic properties. Here, ferroferric oxide@N-doped residual carbon (Fe 3 O 4 @NRC) composites were successfully fabricated by decorating NRC with Fe 3 O 4 nanoparticles via a facile chemical co-precipitation method. The RC was obtained through acid treatment to remove the inorganic minerals in coal gasification fine slag. The structure, composition, thermal stability, morphology, and related EM parameters of the as-fabricated Fe 3 O 4 @NRC composites were thoroughly tested via analytical techniques. Notably, both the Fe 3 O 4 @NRC-2 and Fe 3 O 4 @NRC-3 composites exhibited superior EMWA capacity. When 40% mass was added, the value of minimal reflection loss ( RL min ) for Fe 3 O 4 @NRC-2 was −37.4 dB, and the effective absorption bandwidth (EAB, RL ≤ −10 dB) reached 4.16 GHz (13.84–18.00 GHz) at a thickness of 1.5 mm. Besides, the value of impedance matching was 1.00 as the RL min was achieved. The results demonstrated that the EMWA performance of the composites could be adjusted by controlling the content of Fe 3 O 4 nanoparticles. The magnetic/carbon composites exhibited superior EMWA performance, thus promoting the resource utilization of residual carbon in coal gasification fine slag from coal gasification. The effective absorption bandwidth of 4.16 GHz and minimal reflection loss of −37.3 dB at 1.5 mm thickness were achieved for the Fe3O4@NRC composites. The dielectric loss originated from dipole plarization and interfacial polarization, conduction loss were beneficial to the enhancement of optimal impedance matching and suitable attenuation capacity. This work can provide a significant guidance for the resource utilization of coal gasification fine slag in the field of electromagnetic wave absorption.

Investigation of crystalographic, morphological and photocatalytic behaviour of Ag doped CuS nanostructures

Intrinsic and extrinsic Cu1-xAgxS (0.0 ≤ x ≤ 0.1) nanostructures (NSs) have been successfully synthesized by a facile chemical co-precipitation method in the presence of 4-methoxy-2-nitroaniline, which acts as a glazing agent. Powder X-ray diffraction (XRD) and electron microscope [High Resolution Transmission Electron Microscope (HR-TEM), Field Emission Scanning Electron Microscope (FE-SEM)] studies have been carried for crystallographic and morphological analyses of synthesized NSs, while spectroscopic studies [UV–visible absorption spectroscopy and Energy Dispersive X-ray Spectroscopy (EDS)] have been carried for quantitative and qualitative analyses. Recorded diffractograms reveal that the synthesized NSs crystalizes in wurtzite (hexagonal) structure having average crystallite size values of 7.36 nm and 6.50 nm for CuS and Cu0.9Ag0.1S, respectively. On the other hand, electron micrographs recorded for the morphological analysis indicate that pristine CuS NSs have flower like morphology with petal length ranging between 30 nm–50 nm along with width ranging between 10 nm–15 nm, whereas Cu0.9Ag0.1S nanostructures have rod like morphology with length and radius varying between 25 nm–70 nm and 6 nm–8 nm, respectively. Spectroscopic studies show that highly pure synthesized NSs have broad absorption profiles in the visible range of electromagnetic spectrum which make them a potential candidate to act as visible light initiated photo-catalysts. Photo-catalytic activity potential of the synthesized NSs has been studied under visible light irradiation using methylene blue (MB) dye as the test contaminant in aqueous media. Photocatalytic activity dependence on the dopant concentration have been thoroughly studied which reveal that the 0.1% Ag doped CuS NSs have maximum degradation of the MB dye ∼75.39%, proving it to be an efficient and cost effective nanophoto-catalyst for waste water treatment.

Visible light active Cu-doped iron oxide for photocatalytic treatment of methylene blue

In recent work, pure α-Fe2O3 (F-1) and series of 5% Cu doped Fe2O3 (CF-5) , 10% Cu doped Fe2O3 (CF-10) and 15% Cu doped Fe2O3 (CF-15) nanoparticles by facile chemical coprecipitation method were synthesized to study the effect of concentration of doping for photocatalytic activity. As prepared F-1, CF-5, CF-10, CF-15 nanoparticles were subjected to X-ray diffraction (XRD) and Fourier transform infra-red (FTIR) techniques to analyse the structural and functional groups features. These characterization techniques confirmed the successful doping of Cu 2+ ions in α-Fe2O3. The crystallite size of synthesized samples was calculated by Scherrer formula. Gradually decline in crystallite size from 18 to 15 nm was observed for undoped to doped samples. Scanning electron microscopic (SEM) analysis expressed that doping of Cu reduced the aggregation of particles and enhanced the surface area of nanoparticles. UV–Visible spectroscopic analysis of synthesized samples was used to calculate the bandgap energy of F-1, CF-5, CF-10, CF-15 nanoparticles i.e., 2.0, 1.7, 1.5, 1.4eV respectively. Narrowing bandgap energy of doped hematite supported to perform excellent photocatalytic activity. Maximum degradation of methylene blue was recorded via CF-10 within 140 min. Higher degradation rate of methylene blue by optimal concentration of CF-10 is due to effective electron trapping ability of photocatalyst.

Structural, Magnetic, and Dielectric Properties of Ultrafine Nickel-Substituted Cobalt Ferrite-Reduced Graphene Oxide Nanocomposites

Nickel-substituted cobalt ferrite–reduced graphene oxide (NCF-RGO) composite was synthesized using a facile one-pot chemical coprecipitation method. The addition of graphene oxide (GO) leads to the decrease in the size of NCF nanoparticles (< 10 nm) present in the nanocomposite, which plays role in controlling their magnetic and dielectric properties. Nickel with a lower ionic radius compared to cobalt, and its substitution in the composite along with the incorporation of GO, exhibits superparamagnetic properties in the blend. A large magnetization of 51.63 emu/g and a high dielectric constant of 3.92 × 106 (at 100 Hz) were also determined for the nanocomposite. High charge-storing capability and tunable magnetization have been developed in this work. Thus the NCF-RGO nanocomposite finds potential application in flexible magnetic storage devices. Nickel-substituted cobalt ferrite-reduced graphene oxide (NCF-RGO) composite was synthesized via the chemical coprecipitation method. A superparamagnetic transition was exhibited by the composite, with an enhanced dielectric constant of 3.92 × 106 at 100 Hz.

Low field magnetic interactions in the transition metals doped CuS quantum dots

Polyvinlypyrrolidone (PVP) capped and magnetic transition metals (TM = Fe, Co and Cr) doped CuS quantum dots (Cu1-xTMxS; x = 0.02 & 0.04) were synthesized by low entropy facile chemical co-precipitation method. The structural, optical and magnetic characterizations of the synthesized QDs were done by using X-ray diffraction (XRD) technique, UV–Vis-NIR absorption spectroscopy, photoluminescence (PL) spectroscopy and superconducting quantum interference device (SQUID) respectively. The low field non-linearity and the presence of coercivity in the M−H loops indicate the presence low field magnetic (spin–spin) interactions between the doped cations.

Poly(catechol) modified Fe3O4 magnetic nanocomposites with continuous high Fenton activity for organic degradation at neutral pH.

Fe3O4 magnetic nanoparticles (MNPs) have been widely used as a recyclable catalyst in Fenton reaction for organic degradation. However, the pristine MNPs suffer from the drawbacks of iron leaching in acidic conditions as well as the decreasing catalytic activity of organic degradation at a pH higher than 3.0. To solve the problems, Fe3O4 MNPs were modified by poly(catechol) (Fe3O4/PCC MNPs) using a facile chemical co-precipitation method. The poly(catechol) modification improved both the dispersity and the surface negative charges of Fe3O4/PCC MNPs, which are beneficial to the catalytic activity of MNPs for organic degradation. Moreover, the poly(catechol) modification enhanced the efficiency of Fe(II) regeneration during Fenton reaction due to the acceleration of Fe(III) reduction by the phenolic/quinonoid redox pair. As a result, the Fenton reaction with Fe3O4/PCC MNPs could efficiently degrade organic molecules, exampled by methylene blue (MB), in an expanded pH range between 3.0 and 10.0. In addition, Fe3O4/PCC MNPs could be reused up to 8 cycles for the MB degradation with negligible iron leaching of lower than 1.5 mg L-1. This study demonstrated Fe3O4/PCC MNPs are a promising heterogeneous Fenton catalysts for organic degradation.