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.

Green and chemical syntheses of silver nanoparticles: Comparative and comprehensive study on characterization, therapeutic potential, and cytotoxicity

The emergence of metallic nanoparticles through green synthesis has garnered significant recognition, shaping global research efforts towards eco-friendly practices, often termed as the green revolution. Specifically, the green synthesis of silver nanoparticles (AgNPs) has made considerable strides in the past decade, becoming a prominent fixture in the realm of science and technology. The study explores the synthesis and characterization of silver nanoparticles (AgNPs) using Cassia fistula L. flowers extract through chemical co-precipitation (CM_AgNPs) and green methods (CFF_AgNPs). Characterization techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), attenuated total reflectance fourier-transform infrared (FTIR), and X-ray diffraction (XRD), revealed irregular morphologies with agglomeration, polycrystalline nature, and intrinsic functional groups involved in capping AgNPs. Antioxidant assessment demonstrated superior antioxidative activity (84.48 %) in green-synthesized nanoparticles compared to chemically synthesized ones (75.87 %), and they exhibited dose-dependent anti-inflammatory effects with IC50 values CFF_AgNPs_30.19 μg/mL and CM_AgNPs _34.14 μg/mL respectively. The lower IC50 value of CFF_AgNPs_30.19 μg/mL signifies finer and better activity due to the presence of phytochemicals present in it. Whereas for CM_AgNPs the IC50 value is a 34.14 μg/mL which is solely due to AgNPs. To ensure the promising therapeutic aspects of AgNPs with a careful assessment of their safety profile, cytotoxicity of AgNPs on HEP3B cancer cells was evaluated through MTT assay, lactate dehydrogenase (LDH) release, and reactive oxygen species (ROS) level measurement. In the in vitro cytotoxicity evaluation, HEP3B demonstrated more pronounced dose-dependent adverse effects upon exposure to CFF_AgNPs compared to CM_AgNPs. This study underscores the bioactive potential of Cassia fistula L. mediated AgNPs, suggesting promising applications in biomedicine with environmental sustainability. The findings contribute to the growing interest in green synthesis methods for metallic nanoparticles and their potential benefits in various fields.

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.

Effect of La2Sn2O7 content on the anti-arc erosion capability of Ag-Ni-La2Sn2O7 composites

La2Sn2O7 has high melting point and excellent thermal stability, which improves the wettability between matrix and reinforcement. In this study, La2Sn2O7 powder was synthesized by chemical coprecipitation method, and Ag-Ni-La2Sn2O7 composites were prepared by vacuum hot-pressing sintering. The effect of La2Sn2O7 content on the arc erosion behavior of Ag-Ni-La2Sn2O7 composites was studied. The Ag-Ni-La2Sn2O7 (85:12:3) composite has the lowest arc energy and the highest breakdown strength. With the increase of La2Sn2O7 content, the defects on the cathode surface decrease and the erosion areas become flat. After arc erosion, the samples generate Ag2O, NiO, La2O3 and SnO2. In this study, the mechanism of La2Sn2O7 to improve the anti-arc erosion capability of composites is mainly enhancing the viscosity of the molten pool by the "pinning" action, consuming energy by the decomposition of La2Sn2O7, and the promotion of arc movement.

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.

Synthesis, characterization and magnetic properties of iron oxide nanoparticles from reverse chemical co-precipitation method

Studying magnetic characteristics of iron oxide nanoparticles was highlighted as a key step in creating potential powder nanomaterials. The occurrence of electron spins parallel to the crystallographic orientations and single domain nanopartilces are the recognized causes of superparamagnetism in bulk magnetite. Nanoparticles whose size could be tuned exhibit this superparamagnetism effect. The reverse co-precipitation process is used to create the current magnetite nanoparticles. The iron oxide nanoparticles were synthesized by reverse chemical coprecipitation method and were confirmed based on XRD data. The room temperature magnetic property was studied and the tiny levels of coercivity and remanence indicate that the samples may exhibit superparamagnetic nature.

Determination of the possibility of the synthesis of Zn-Al layered double hydroxides, intercalated with peroxyanions, as a perspective solid disinfectant

Infectious diseases in the modern world pose a significant threat to humanity in the form of epidemics and pandemics. To prevent and combat them, it is necessary to carry out antiseptic and disinfectant treatments of various environments, household and industrial surfaces, as well as wounds of various origins. Double-layer hydroxides intercalated with peroxyanions as active oxygen compounds are promising materials for this. In order to determine the possibility of obtaining Zn-Al double-layer hydroxide intercalated with peroxylactic acid anions, samples were synthesized by the method of chemical co-precipitation in the presence of peroxylactic acid at controlled pH (8, 10) and t=20 ℃. The properties of the synthesized samples were investigated. The content of active oxygen (in terms of H2O2) was determined by the method of iodometric titration with the calculation of the percentage of hydrogen peroxide that was intercalated in double layered hydroxides, remained in the mother solution or was lost. The crystal structure was studied by X-ray phase analysis, the yield of samples was determined gravimetrically, and sedimentation was determined by measuring and normalizing the thickness of the sediment layer. It was found that the samples synthesized at pH=8 and 10 are biphasic and consist of an oxide phase and a double-layer hydroxide phase. The determined content of active oxygen (in terms of H2O2) in the samples synthesized at pH=8 (0.533 %) and at pH=10 (0.876 %) confirms the success of the synthesis of Zn-Al-peroxylactate double layered hydroxides. Synthesis at elevated pH is promising. A low percentage of H2O2 intercalation was revealed – 4.03–6.54 %, the majority of hydrogen peroxide (82.36-94.44 %) remains in the mother solution. The yield of the synthesized samples was determined to be 61.9 % and 79.5 % at synthesis pH of 10 and 8, respectively. The sedimentation properties of the samples were studied and their improvement was shown when the pH of the synthesis was increased

Enhanced dye-sensitized solar cell performance and electrochemical capacitive behavior of bi-functional ZnO/NiO/Co3O4 ternary nanocomposite prepared by chemical co-precipitation method

Increasing prerequisites for sustainable energy storage and conversion technologies have necessitated the exploration of advanced materials with improved properties. Here, we present the synthesis and characterization of ZnO nanoparticles (NPs), ZnO/NiO, ZnO/Co3O4 and ZnO/NiO/Co3O4 NCs as promising bi-functional materials for dye-sensitized solar cell (DSSC) and electrochemical energy storage applications. A facile chemical co-precipitation approach was followed to synthesize pure ZnO NPs, ZnO/NiO, ZnO/Co3O4 and ZnO/NiO/Co3O4 NCs. The structural and morphological analyses revealed the successful integration of ZnO, NiO, and Co3O4 NPs and also the formation of well-defined core-shell and homogenous nanocomposite structures. The XRD and HRTEM analyses confirmed the crystalline nature and nanoscale morphology of synthesized materials, respectively. The photovoltaic performance of DSSC fabricated using ternary ZnO/NiO/Co3O4 NC photoanode showed optimum dye-loading and best solar to electrical energy conversion efficiency with Jsc of 11.29 mA cm−2 and ƞ of 4.66%, which was considerably higher than the DSSC fabricated using pure ZnO NPs photoanode (ƞ = 2.01%). The increment in photocurrent density (Jsc) could be ascribed to the perfect band alignment of NiO and Co3O4 NPs in the ternary NC. Further, the ZnO/NiO/Co3O4 NC photoanode integrated DSSC disclosed 97% retainment in energy conversion efficiency even after 10 days of operation. The electrochemical performance of supercapacitor fabricated using ternary ZnO/NiO/Co3O4 NC showed high specific capacitance of 534.7 Fg−1 at 1 Ag−1 with favourable rate ability (∼52% at 16 Ag−1), good cyclic stability (91.07%) and low internal resistance. Moreover, the ZnO/NiO/Co3O4 NC at a current density of 2 Ag−1 exhibited a significantly high capacitance value of 463.1 Fg−1, which was 1.93, 1.58 and 1.22 times greater than ZnO NPs, ZnO/Co3O4 NC and ZnO/NiO NC, respectively.

Field-induced magnetorheological study towards the active magneto-viscoelastic behavior of stable MnFe2O4 magnetic nanofluid

This work presents the fine-tuned synthesis of MnFe2O4 oleic acid-coated magnetic nanoparticles (MNPs) by the chemical co-precipitation method. The X-ray photoelectron spectroscopy (XPS) was utilized to investigate the elemental composition and oxidation state of oleic acid-coated MnFe2O4 MNPs. The Fourier transform infrared spectroscopy (FTIR) spectra were used to confirm the functional groups in the oleic acid-coated MnFe2O4 magnetic nanoparticles. The spherical shape of MnFe2O4 MNPs is confirmed by Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM) techniques. Zeta potential (ζ) measurements were performed to confirm the stability of MnFe2O4 magnetic nanofluid (MNF). Magnetic measurements (M−vs−H) reveal the saturation magnetization, Ms = 20.3 emu/g and coercivity, HC = 30 Oe, confirming the single domain superparamagnetic nature at 300 K. Field-induced shear thinning behavior of the MnFe2O4 magnetic fluid is confirmed by a power law, η = c γn + n∞ and steady-state behavior measurements. Magneto viscous effect initially increased at a low shear rate of 20 s−1 and then decreased at a higher shear rate of 100 s−1, which confirms the stability of the MnFe2O4 magnetic fluid. Also, the highest deflection angle, θ = 243 m.rad of MnFe2O4 magnetic fluid was observed at a moderate shear rate 100 s−1 and a high magnetic field of 1.2 T, while the lowest value of deflection angle, θ = 65 m.rad was observed in the absence of magnetic field. In contrast, the storage modulus (G') is greater than the loss modulus (G''), in corroboration with the viscoelastic-to-viscous behavior of MnFe2O4 magnetic fluid.

Structure and morphology modification of ZnO nanocrystals via substitutional cobalt doping for enhanced electrochemical activity

This study investigated the electrochemical performance of the morphologically and structurally modified Co-doped ZnO nanocrystals synthesized via the chemical co-precipitation method. The structural properties were characterized by XRD, where the lattice parameters and volume got smaller with the increasing amount of Cobalt doping. The compositional analyses showed that 1.5 and 2.5 at% of Cobalt was present in the Co-doped ZnO nanocrystals. The FT-IR analyses showed that Zn–O (tetrahedral) and Zn–O (octahedral) vibrational modes are present for the precipitated ZnO-based nanocrystals. Besides that, the characteristic Raman spectra mode for ZnO displayed redshift, and more modes were activated, which showed a change in the defect chemistry after the cobalt substitution into the ZnO host lattice. A significant change was observed in morphology where the pristine ZnO formed nanoflower composed of nanoflakes and the Co-doped ZnO nanoparticles formed nanospheres. Lastly, cyclic voltammetry was performed at different scan rates where typical Faradaic peaks were observed for all the samples, and the electrochemical performance was increased with the small amount of Co doping into the ZnO lattice. The samples showed improved pseudocapacitive behavior, suggesting that Cobalt doped ZnO nanoparticles synthesized via the chemical co-precipitation method can be a potential electrode material for pseudocapacitor applications.

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.

Evolution of Ni-induced orthorhombic phase in SnO2: Influence of Ni on the optical and photocatalytic properties

This paper presents the impact of nickel doping on the structural, optical and photocatalytic characteristics of Sn1-xNixO2 (x = 0, 0.3, 0.05, 0.07) nanoparticles. The samples are synthesized via the chemical co-precipitation method. Information on the structural properties of the samples is obtained via the Rietveld refinement technique. As the dopant concentration increases, a partially stable orthorhombic phase emerges and becomes prominent, indicating a correlation with the amount of Ni dopant. This orthorhombic phase arises during the transformation from the amorphous state to a more stable crystalline phase. The FESEM-EDAX analysis demonstrates the uniform distribution of agglomerated particles. Additionally, the Raman data provides information related to surface defects and vacancies. A minor increase in the band gap value is detected, and this observed blue shift can be attributed to the Burstein-Moss effect. The samples exhibit a strong blue emission, primarily attributed to surface defects and states, particularly due to the oxygen vacancies. The CIE coordinates show an increase in blue colour purity, making the samples suitable for blue components in white-light emitting diodes. However, the photocatalytic study reveals only partial degradation of methylene blue under visible light conditions.

Synthesis of nickel-copper layered double hydroxides for asymmetric supercapacitors by low-temperature chemical co-precipitation method

Synthesis of nickel-copper layered double hydroxides for asymmetric supercapacitors by low-temperature chemical co-precipitation method

In English

Currently, textile and food industries produce a significant volume of sewages containing azo dyes and other organic pollutants. These effluents are serious environmental threats, so new methods for their treatment and the degradation of azo dyes are attracting much attention. Composite materials based on TiO2 modified by noble metals and nanoceria show high activity in the photodegradation of organic contaminates and are proposed for hydrogen synthesis as well. To optimize the treatment of contaminants, different processes can combine including the strategies of adsorption, photoluminescence, photocatalysis, etc. The synthesized TiO2-based nanomaterials (sols, powders) will be exploited for bioremediation due to their small size and surface plasmon resonance from noble metals. Binary nanocomposites based on TiO2 were obtained by the chemical co-precipitation method from solutions of titanium tetraisopropoxide (TTIP) and inorganic salts of cerium, silver, and palladium. It has been stated that TiO2 is represented by anatase with primary particle size (CSR) from 8.5 to 16.8 nm, depending on the nature and concentration of the dopant. It is shown that Ag is reduced on the surface of anatase particles and blocks their growth, while Pd and Ce penetrate the titanium dioxide matrix in the form of small clusters with the deformation of the anatase crystal lattice. Nanocomposite particles formed loose and fragile aggregates, which spontaneously dispersed in solutions of dyes with the formation of colloid-stable sols, required the use of a centrifugal field for their sedimentation. Nanoparticles of TiO2&Pd were electronegative and others were electropositive according to the values 4.1÷9.6 of ZPC (zero point of charge). It was shown that the particles of all composites sorbed Methylene Blue (MB) without photocatalytic activity under the visible light to any dye. Moreover, anionic dyes such as Orange-G (Or-G) and Methyl Orange (MO) were excellently discolorated in the presence of TiO2&Pd system; cationic dyes of MB and Rhodamine B (RhB) discolorated too with the TiO2, TiO2&CeO2, and TiO2&Ag systems under UV light action. As such, photocatalysis tests showed that Orange-G’s and MO’s discoloration was higher for TiO2&Pd (2 wt. %) and TiO2 systems with the correlation coefficient R2 0.999.

Microwave-assisted synthesis, characterization, and oxytetracycline antibiotic sorption performance of a novel magnetic nanohybrid material: MnFe2O4@black cumin solid waste-derived activated carbon

Using waste resources to synthesize functional materials without polluting the environment is important for sustainable life and development. In the present study, a novel magnetically separable activated carbon nanohybrid (MnFe2O4@BAC) was produced by using the microwave-assisted chemical co-precipitation method of industrially processed black cumin solid waste-derived activated carbon (BAC) and manganese ferrite nanoparticles (MnFe2O4). It was characterized by VSM, XRD, Raman, BET, SEM-EDX, FTIR, Boehm titration, and pHPZC analysis techniques. Spinel MnFe2O4 nanoparticles significantly affected the pore properties of BAC. MnFe2O4@BAC exhibited a saturation magnetization property of 14.6 emu/g. Also, the optimal sorption conditions of oxytetracycline (OTC), which was chosen as a model to test the antibiotic sorption ability from water, were decided according to the optimum influences of operational variables. The kinetic and isotherm results best described the pseudo-second-order and Langmuir models, respectively. The maximum OTC sorption ability of MnFe2O4@BAC was determined as 591.7 mg/g under specified optimal sorption conditions. Thermodynamic parameters were calculated to show that the sorption is spontaneous volitional and endothermic. The spent MnFe2O4@BAC was accumulated after sorption using an external magnetic field for subsequent reuse and showed excellent reusability stability.

Improving gallic acid detection in plant samples: Fabrication and optimization of a sensitive and selective NiO-supported carbon paste electrode

In this study, we successfully prepared a modified nickel oxide (NiO) carbon paste electrode to detect gallic acid (GA). NiO nanoparticles were synthesized by the simple, organic solvent-free chemical coprecipitation method, and the electrochemical properties of the electrode and GA were thoroughly investigated using CV, SWV, and EIS, while morphological properties were examined using ICP-OES, TEM, SEM, and XRD. Excellent catalytic characteristics are displayed by the developed material which facilitates the interaction of the target with the electrode surface. The obtained electrochemical information showed that the incorporation of NiO nanoparticles to the carbon paste electrode effectively facilitates electron transfer processes and enriches the catalytic response of the carbon paste electrode. The fabricated NiO/CPE sensor showed a satisfactory linear relationship between peak current and GA concentration in the broad range of 0.2–100 μM and 100–200 μM with a low detection limit of 0.04 μM and limit of quantification of 0.12 μM at pH 3 of BRBS as supporting electrolyte. The selectivity of the proposed method was satisfactory, with acceptable stability, considerable repeatability, and accurate reproducibility. Moreover, the good practicability performance could be effectuated at the NiO/CPE sensor for the quantitative analysis of GA in bourtree, walnut, primrose, and chamomile tea samples. The results were compared with the standard DPPH test and statistical processing of the results was performed, which confirmed the excellent agreement between the two methods. The developed method can provide a cost-effective, rapid, selective, and sensitive means for GA monitoring. When compared to other works, the developed technique has a wider linear range and lower LOD and LOQ, which makes this work a very important reference for the highly sensitive analysis of GA in the field of food safety.

Effect of Gd3+ ion doping on structural, optical, magnetic and dielectric properties on superparamagnetic Mg0.5Zn0.5Fe2−xGdxO4 (0 ≤ x ≤ 1) nanoparticles synthesized via oleic acid assisted chemical co-precipitation method

In the present study, different compositions having general formula Mg0.5Zn0.5GdxFe2−xO4, (x = 0, 0.025, 0.050, 0.075, 0.1) were synthesized using chemical co-precipitation method. The substitution of Gd3+ ions have exhibited profound impacts on the structural, morphological, magnetic, and optical parameters of Mg-Zn ferrites. Single-phase cubic spinel structure has been substantiated by X-ray diffractometer (X-ray diffraction, XRD) analysis for all compositions without any contamination peak. The values of the lattice constant and X-ray density both show an increasing trend when the Gd3+ ion concentration increases. (Fourier transformed infrared spectroscopy) FTIR spectra recorded in the mid-infrared region (4000–400 cm−1) exhibit two main absorption bands associated with the Oh and Td sites within the frequency range of 400–600 cm−1. Morphological studies using (High-resolution transmission electron microscopy) HR-TEM analysis reveal agglomeration of nanoparticles and the average particle size lies between 8 and 9 nm. Maximum magnetization displays an erratic trend with increasing Gd3+ ion concentration, although both retentivity and coercivity decreases. The hysteresis curve for samples of differing ratios of Gd3+ ions demonstrated the superparamagnetic nature. Tauc’s plot was employed to calculate the energy bandgap (Eg) of synthesized nanoparticles and Eg value were observed to decline from 3.563 eV to 3.521 eV with an increasing Gd3+ ion concentration. Impedance analyzer was used in the frequency range of 100 Hz–100 MHz to study dielectric properties at room temperature. The dielectric parameters declined as the frequency values increased. Due to lower values of dielectric parameters in Gd3+ ion doped Mg–Zn nano-ferrite, these materials are suitable in the fabrication of devices that need to operate at high frequencies such as switching memory storage devices. Moreover, these materials are appropriate for application in ferrofluids and medicinal treatments such as magnetic hyperthermia because of their low coercive field value.

Construction of highly efficient carbon cloth-supported S-scheme Co3O4/AgIO4 heterojunction for photocatalytic degradation of Rhodamine B organic dye

The development of effective methods for the synthesis of supported photocatalysts instead of dispersive powdery photocatalysts has received great attention. Herein, a flexible visible-light-driven carbon cloth-supported Co3O4/AgIO4 composites was successfully prepared by combining electrodeposition and chemical coprecipitation method. After 40 min of visible-light illumination, 99.2 % of the rhodamine B can be degraded by carbon cloth-supported Co3O4/AgIO4 composites with electrodeposition duration of 50 min, showing a highest reaction rate constant of 10.5 × 10−2 min−1 which exceeds that of CC/Co3O4 and CC/AgIO4 by a factor of 58.39 and 2.67 times, respectively. The band structures of the samples were studied by valence band X-ray photoelectron spectroscopy, ultraviolet photoemission and theoretical calculations. The capture experiments confirmed that positive holes and the superoxide radicals are two main reactive species participating in the degradation of rhodamine B. The excellent photocatalytic reactivity can be attributed to the successful construction of S-scheme heterojunction between Co3O4 and AgIO4. The Co3O4/AgIO4 heterojunction not only inhibited the rapid recombination of charges but also reserved the oxidation and reduction ability of the holes in the valence band of AgIO4 and electrons in the conduction band of Co3O4. The work is of great significance in the development of carbon cloth-supported photocatalysts with good recyclability for practical applications of wastewater treatment.

Modifying the aquatic toxicity of Co3O4 nanoparticles in exposed microalgae by CTAB mediated synthesis

Besides unique physical and chemical properties, Cobalt oxide nanoparticles (Co3O4 NPs) are ecotoxic in nature that limits their industrial applications. The present work assesses the ecotoxic effects of Co3O4 NPs in aquatic environments. Chlorella minutissima (freshwater microalgae) and Tetraselmis suecica (marine microalgae) were used as aquatic test species. Two forms of Co3O4 NPs were used; one was synthesized with CTAB (COCTAB NPs) and the other without CTAB (CO NPs). NPs were synthesized with the chemical co-precipitation method and further characterized. The average crystallite size of CO NPs and COCTAB NPs were 12–18 nm and 22–28 nm respectively. Aggregation occurred with both NPs but the increased hydrodynamic size was measured with COCTAB NPs in BG 11 (1465 nm) and f/2 media (1951 nm). The interaction of COCTAB NPs with microalgae showed a lower % growth inhibition effect than CO NPs. The 72 h EC 50 (effective concentration of a chemical having 50% of its impact) of COCTAB NPs for C. minutissima (50.71 mg/L) and T. suecica (63.92 mg/L) was higher than the corresponding EC 50 of CO NPs. Further, % chlorophyll – a content and % LDH (lactate dehydrogenase) release retained less affected in microalgae treated with COCTAB NPs. FTIR spectra and Zeta potential revealed that the use of CTAB in CO3O4 NPs synthesis has lowered toxicity possibly by preventing the cellular attachment of NPs and its ionic dissolution. The increased hydrodynamic size and colloidal instability also restricted the NPs from binding with cells crossing membrane barrier and causing any internal damage.