Microwave-assisted Co-precipitation Method Research Articles

Microwave assisted synthesis of NiMn<sub>2</sub>O<sub>4</sub> as electrode material for supercapacitor applications

In this work, spinel NiMn2O4 was successfully synthesized through microwave assisted co-precipitation method and followed by calcination at 500°C. The crystal structure and the presence of functional groups in NiMn2O4 were characterized through X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The surface morphology was examined by field emission scanning electron microscopy (FE SEM). From the BET analysis surface area and average pore diameter of the mesoporous NMO nanoparticles are calculated to be 10.513 m2g-1and 8.55nm. The electrochemical performance of material as electrode material for supercapacitor applications was analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance of the NMO electrode increased from 290.56 F/g to 751.57F/g with increase concentration from IM KOH to 6M KOH at scan rate of 5mV/s. These results indicate spinel NiMn2O4 as a promising candidate for high performance energy storage applications.

In situ constructed Bi5O7I/NiO-NF heterojunction on 3D nickel foam for photocatalytic sulfamerazine degradation: Structure-performance, application, and mechanism

Photocatalysis is a promising technology for water purification, but the inadequate separation of photogenerated charge carriers and light utilization efficiency limits its practical application. Herein, a highly solar-responds photocatalyst Bi5O7I/preoxidized nickel foam (Bi5O7I/NiO-NF) with p-n heterojunction was constructed by impregnation and microwave-assisted co-precipitation method to remove typical antibiotic efficiently. The special pretreatment is conducive to the formation of NiO on the NF surface, which participates in the construction of p-n heterogeneous structures and strengthens the bonding force between NiO-NF and surface Bi5O7I. The macroscopic renewable Bi5O7I/NiO-NF could effectively degrade sulfamerazine (SMR) nearly 100 % under sunlight irradiation and be convenient for separating from aqueous. Variety pollutants are degraded with high efficiency in the solar Bi5O7I/NiO-NF system, and the system performs the resistance to co-existing ions (≥89 % removal efficiency) and water matrix interference (≥95 % removal efficiency). Quenching experiments and electron paramagnetic resonance spectroscopy characterization results indicate that h+, 1O2 and O2− are the dominant reactive substances in SMR elimination. Based on the DFT calculation and quadrupole-time of flight-liquid chromatography/mass spectrometry (Q-TOF-LC/MS) detection, C-S and N-S bonds tend to be attacked in the SMR degradation pathway. This work opens up novel insights for constructing efficient macroscopic photocatalysts for practical water treatment.

Photocatalytic degradation of Acid Red 18 by synthesized AgCoFe2O4@Ch/AC: Recyclable, environmentally friendly, chemically stable, and cost-effective magnetic nano hybrid catalyst

Chitosan (Ch) is a linear biodegradable natural carbohydrate polymer and the most appealing biopolymer, such as low-cost biodegradability, biocompatibility, hydrophilicity, and non-toxicity. In this case, Ch was utilized to synthesize AgCoFe2O4@Ch/Activated Carbon (AC) by the modified microwave-assisted co-precipitation method. The physical and chemical structure of magnetic nanocomposites was analyzed and characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), Diffuse Reflection Spectroscopy (DRS), Value stream mapping (VSM), Fourier transform spectroscopy (FTIR) and BET. The effects of various parameters on the removal of dye (Acid Red18), including catalyst dose, dye concentration, pH, and time were studied. Results showed that the highest removal efficiencies were 96.68 % and 84 % for the synthetic sample and actual wastewater, respectively, in optimal conditions (pH: 3, the initial dye concentration: 10 mgL−1, the catalyst dose: 0.14 gL−1, time: 50 min). Mineralization, according to the COD analysis, was 89.56 %. Photocatalytic degradation kinetics of Acid Red 18 followed pseudo-first order and Langmuir-Hinshelwood with constants of kc = 0.12 mg L−1 min−1 and KL-H = 0.115 Lmg−1. Synthesized photocatalytic AgCoFe2O4@Ch/AC showed high stability and after five recycling cycles was able to remove the pollutant with an efficiency of 85.6 %. So, the synthesized heterogenous magnetic nanocatalyst AgCoFe2O4@Ch/AC was easily recycled from aqueous solutions and it can be used in the removal of dyes from industries with high efficiency.

Achieving High Dielectric Constant in γ-Al2O3-rGO Nanocomposite Prepared by Microwave-Assisted Co-Precipitation Method

In this study, γ-Al2O3-GO, and γ-Al2O3-RGO nanocomposites were synthesized by the microwave-assisted coprecipitation method to study their electrical properties. XRD pattern and EDAX confirmed that the nanocomposites successfully were synthesized. TEM studies confirmed that γ-Al2O3 NPs formed into spherical particles and that these particles were dispersed randomly on RGO in contrast to γ-Al2O3-GO and Al2O3. At room temperature, the frequency dependence of the dielectric constant, dielectric loss, and AC conductivity of the synthesized samples were studied. Our findings indicate that the prepared nanocomposite RGO-Al2O3 has a dielectric constant of 16 at 106 Hz, which is twice the dielectric constant of commercially available Al2O3 which is mainly due to a more conductive network.

Facile and green synthesis of recyclable, environmentally friendly, chemically stable, and cost-effective magnetic nanohybrid adsorbent for tetracycline adsorption

Antibiotic contamination of water sources, particularly tetracycline (TC) contamination, has emerged as one of the global issues that needs action. In this research, ZnCoFe2O4@Chitosan (Ch) as a magnetic nanohybrid adsorbent was synthesized using the microwave-assisted co-precipitation method, and their efficiency for the TC adsorption process was investigated. FESEM (Field Emission Scanning Electron Microscope), EDX (Energy Dispersive X-ray), Mapping and line Scan, XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared Spectrometer), VSM (Vibrating Sample Magnetometer), Thermogravimetric analysis (TGA) and BET (Brunauer Emmett Teller) techniques were used to check and verify its physical and chemical properties. The removal of TC via the adsorption process from synthetic and real wastewater samples was investigated. The factors determining the TC adsorption process, comprising tetracycline concentration (5–30 mg/L), adsorbent dosage (0.7–2 g/L), contact time (2–45 min), and pH (3–11), were evaluated. The removal effectiveness for the synthetic sample and the real wastewater sample was 93 % and 80 %, respectively, under the ideal TC adsorption process parameters of pH 3, adsorbent dosage 1 g/L, TC initial concentration 5 mg/L, and contact time 30 min. According to kinetic and equilibrium studies, the adsorption of TC by ZnCoFe2O4@Ch follows pseudo-second-order kinetics and the Freundlich isotherm. Additionally, it was determined through the analysis of thermodynamic data that the process of exothermic adsorption is spontaneous and is followed by a decrease in disorder (ΔH = −15.16 kJ/mol, ΔS = −28.69 kJ/mol, and ΔG = −6.62 kJ/mol). After five cycles of recovery and regeneration, the ZnCoFe2O4@Ch magnetic nanocomposite was able to remove 65 % of the TC pollutant and had good chemical stability. The results showed that the magnetic nano-adsorbent ZnCoFe2O4@Ch is a novel magnetic nano-adsorbent with high adsorption capacity that can be utilized to eliminate pharmaceutical contaminants from aqueous solutions.

Enhancement of dielectric and ferroelectric properties of (Sr, Ni) Co-doped BaTiO3 ceramics

In the present study, systematic investigations on dielectric and ferroelectric properties of pure and (Sr, Ni) co-doped BaTiO3 nanocrystalline powder samples fabricated via microwave-assisted co-precipitation method have been reported. XRD patterns divulge the formation of mono-phase tetragonal crystal structure with P4mm space group. The fingerprint bands in the FTIR spectra further assure the formation of desired crystal structure. The dielectric responses have been examined by virtue of the universal dielectric response mechanism with remarkable improvement in the dielectric properties for the (Sr, Ni) co-doped sample. The P-E loop measurement corroborates ferroelectricity in the system and augmentation in the maximum polarization for the co-doped sample. The improved dielectric and ferroelectric properties in (Sr, Ni) co-doped BaTiO3 suggest its potential in various technological applications.

Outstanding performance of hierarchical alumina microspheres for boron removal in the presence of competing ions

Developing efficient materials for the removal of boron from aqueous solutions is becoming an important task to overcome boron pollution. Herein, we present hierarchical alumina microspheres (HAM) as an outstanding adsorbent, synthesized via a microwave-assisted co-precipitation method. The microstructure, morphology, and textural characterization of the HAM particles carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed hollow γ-Al2O3 particles with a porous dandelion-like shape and an average size of 1.5 μm. The analysis of the adsorption data indicated that the adsorption was homogeneous in a single layer and that chemical adsorption was the controlling step in the process. The adsorption capacity obtained at an initial concentration of 800 mg·L−1 was 51.60 mg·g−1, and the theoretically calculated maximum adsorption capacity using the Langmuir model was 138.50 mg·g−1, which outperforms previously reported adsorbents. The determination of thermodynamic parameters indicated that the adsorption is an exothermic and non-spontaneous process. The XPS spectra of HAM after adsorption indicated the formation of Al-O-B bonds. Of particular interest for industrial applications, the HAM adsorbent showed excellent selectivity for boron in the presence of competing cations or anions and at different ionic strengths. In addition, HAM maintained a high adsorption capacity after five consecutive adsorption/desorption cycles. These findings highlight the potential of HAM as a highly microporous material for boron removal in real industrial applications.

CuCoFe2O4@AC magnetic nanocomposite as a novel heterogeneous Fenton-like nanocatalyst for Ciprofloxacin degradation from aqueous solutions

CuCoFe2O4@Activated Carbon (AC) was synthesized by a fast, simple, and green microwave-assisted coprecipitation method, and then used as a new heterogeneous magnetic nanocatalyst in Fenton-like reaction for ciprofloxacin (CIP) degradation from aqueous media. CuCoFe2O4@AC was characterized by Field emission scanning electron microscopy (FE-SEM), Energy-Dispersive Spectroscopy (EDS), Mapping, Line scan, Fourier-transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), X-Ray diffraction analysis (XRD), vibrating-sample magnetometer (VSM), and Brunauer–Emmett–Teller (BET) techniques. The characterization results showed that the CuCoFe2O4@AC nanocomposite was in the ferrite phase with a mesoporous, uniform, quasi-spherical surface and a particle size of about 25 nm. The total volume of single-point adsorption pores was equal to 0.22 cm3 g−1 and the specific surface area was determined to be 199.54 m2 g−1. This nanocomposite had good thermal stability with high magnetic strength. In the presence of H2O2, the synthesized nanocomposite provided a Fenton-like reaction for CIP removal from aqueous solutions. The investigation of this process showed that neutral pH, 1 g L−1 of the nanocomposite, and 73.5 mM of H2O2 were the optimal conditions for CIP removal with an initial CIP concentration of 20 mg L−1. The maximum removal efficiency of 95.77% was attained after 120 min of contact time under the optimum conditions. The CIP degradation during this Fenton-like process followed a pseudo-first-order kinetic model with rate constants (Kapp) of 0.01 min−1. Finally, the CIP removal efficiency after 5 cycles of recovery and regeneration of CuFe2O4@AC was 87.65%. The excellent performance and high catalytic activity of CuCoFe2O4@AC in Fenton-like reaction for CIP removal make it have potential application foreground in the treatment of pharmaceutical wastewater.

Ce-metal organic framework and reduced graphene oxide co-enhanced the H2 evolution ability of CdS/single crystal ZnO nanorod photocatalyst

To enhance the photocatalytic H2 production capacity of reduced graphene oxide/CdS/single crystal ZnO nanorod (RGOCZ) ternary material, Ce-organic framework [UiO66-(Ce)]/rGO/CdS/single crystal ZnO nanorod (URGOCZ) quaternary material was prepared by microwave-assisted co-precipitation method, and the influence of UiO66-(Ce) content on the photocatalytic performance of quaternary material was analyzed. The experimental study shows that RGOCZ ternary material is anchored in the surface of the UiO66-(Ce), and the photocatalytic H2 evolution capacity of RGOCZ ternary material is enhanced by UiO66-(Ce) significantly. When 15 mL UiO66-(Ce) solution (0.4 g/L) is added, the photocatalytic H2 evolution efficiency of 15URGOCZ quaternary material reaches 10.55 mmol g−1 h−1.

Synthesis of Hematite-Zeolite Nanocomposites and Its Application as Catalyst in Aquathermolysis Reaction in Intermediate Crude Oil

Non-conventional crude oil has 70% of total heavy crude oil reserves and potentially as an energy source. The enhancement of non-conventional crude oil production can be done by utilizing the Enhanced Oil Recovery (EOR) technique with aquathermolysis reaction. The nanocomposite of Activated Hematite-Zeolite has the best properties as a catalyst to provide aquathermolysis on crude oil. These materials were successfully synthesized by using the microwave-assisted co-precipitation method. The XRD pattern represents mixing both hematite and zeolite in mordenite structure at 2θ equal 6.57o; 9.77o; 19.65o; 22.36o; 25.72o; 26.36o and at 30.1o; 35.6o; 40.9o, respectively. A reduction in a viscosity of crude oil occured after the aquathermolysis test was run by nanocomposites about 30.03% and simultaneously enhance the ratio of C-H saturated. Hence, it had improved crude oil quality with larger molecules in crude oil divided into small molecules due to breaking C-C bonds.

Electrochemical and electronic structure properties of high-performance supercapacitor based on Nd-doped ZnO nanoparticles

Recently, hybrid supercapacitors gained the interest of energy experts because of their high energy/power density and long lifespan. In this manuscript, Zn1-xNdxO (x = 0.00, 0.01, 0.03, and 0.05) nanoparticles were synthesised using the microwave assisted co-precipitation method and characterized using XRD, Raman, TEM, XAS, and electrochemical analyses.The HR-TEM images confirmed that all of the samples exhibited spherical morphologies with average particle sizes in the range of 17–20 nm. The XRD and Raman spectroscopy studies infer that crystallinity enhances with increase in the doping concentration. The Nd ions were revealed to possess a valence state of +3, while the Zn ions had a valence state of +2, confirmed from XAS analyses. The electrochemical analysis showed that 3 % Nd-doped ZnO electrode exhibited the maximum specific capacitance (SC) of 154 F/g, at a current density of 2.5 A/g and the best cycle stability when compared to the undoped and other Zn1-xNdxO samples (retaining 92 % after 1000 cycles). The specific capacitance of undoped ZnO determined at a current density of 2.5 A/g was found to be 21 F/g. The energy density and specific power of a 3 % Nd3+-doped ZnO supercapacitor were measured at 7.36 Wh/kg and 730 W/kg, respectively. The electrochemical results suggest that Nd3+-doped ZnO material would serve as an electrode material for supercapacitors application.

A bacterial cellulose-based LiSrVO4:Eu3+ nanosensor platform for smartphone sensing of levodopa and dopamine: point-of-care diagnosis of Parkinson's disease.

Among the catecholamines, dopamine (DA) is essential in regulating multiple aspects of the central nervous system. The level of dopamine in the brain correlates with neurological diseases such as Parkinson's disease (PD). However, dopamine is unable to cross the blood-brain barrier (BBB). Therefore, levodopa (LD) is used to restore normal dopamine levels in the brain by crossing the BBB. Thus, the control of LD and DA levels is critical for PD diagnosis. For this purpose, LiSr0.0985VO4:0.015Eu3+ (LSV:0.015Eu3+) nanoplates were synthesized by the microwave-assisted co-precipitation method, and have been employed as an optical sensor for the sensitive and selective detection of catecholamines. The synthesized LSV:0.015Eu3+ nanoplates emitted red fluorescence with a high quantum yield (QY) of 48%. By increasing the LD and DA concentrations, the fluorescence intensity of LSV:0.015Eu3+ nanoplates gradually decreased. Under optimal conditions, the linear dynamic ranges were 1-40 μM (R2 = 0.9972) and 2-50 μM (R2 = 0.9976), and the detection limits (LOD) were 279 nM, and 390 nM for LD and DA, respectively. Herein, an instrument-free, rapid quantification visual assay was developed using a paper-based analytical device (PAD) with LSV:0.015Eu3+ fixed on the bacterial cellulose nanopaper (LEBN) to determine LD and DA concentrations with ease of operation and low cost. A smartphone was coupled with the PAD device to quantitatively analyze the fluorescence intensity changes of LSV:0.015Eu3+ using the color recognizer application (APP). In addition, the LSV:0.015Eu3+ nanosensor showed acceptable repeatability and was used to analyze real human urine, blood serum, and tap water samples with a recovery of 96-107%.

Microwave-assisted co-precipitation preparation of CuFe2O4 photo-Fenton degradation tetracycline: Characterization, efficacy, stability in complex water quality and mechanism

A magnetic copper ferrite (CuFe2O4) photocatalyst was successfully synthesized by the modified microwave-assisted co-precipitation method to improve the removal performance of tetracycline (TC) and the reusability of a photocatalyst. A series of tests indicate that microwaves could reach the inside of the material quickly and uniformly with its energy so that CuFe2O4 exhibited a more significant specific surface area, magnetic intensity, and separation efficiency of photogenerated electron-hole pairs. CuFe2O4 reached superior photo-Fenton performance of TC in the presence of Cl-, NO3–, HCO3–, HPO42–, SO42– and humic acid, as well as deionized water, river water, and secondary effluent. Ten recycling tests in these three different water quality backgrounds confirmed the stability and remarkable activity of CuFe2O4, with the removal rate only decreasing by 2.0 %, 1.5 %, and 2.1 %, respectively. Free radical capture experiments as well as electron spin resonance suggest that·OH and O2·- were mainly involved in the degradation of TC, and the photo-Fenton degradation mechanism and equations were proposed. Toxicity evaluation declared that CuFe2O4 photo-Fenton degradation of TC was a safe and promising technology. This study offered prospects of magnetic CuFe2O4 prepared by the modified microwave-assisted co-precipitation method in TC wastewater treatment.

Preparation and photocatalytic H2 production property of graphene oxide/CdS/single crystal ZnO nanorod ternary hybrids

In order to further improve the photocatalytic H2 production ability of CdS/single crystal ZnO nanorod heterostructure (CZ), graphene oxide/CdS/single crystal ZnO nanorod hybrid (GCZ) were synthesized by microwave-assisted co-precipitation method, and the influence of graphene oxide (GO) content on the properties of ternary materials was tested. Experimental results exhibit that GO further enhance the photocatalytic H2 production capacity of CZ material. When GO wt% is 2.91%, the as-prepared products have the best photocatalytic H2 production capacity, which its average H2 production rate is 6.511 mmol g−1 h−1. The enhancement for H2 production capacity benefits from increasing specific surface area, reducing bandgap energy of ZnO and accelerating the migration rate of photo-induced carriers due to the superior property of GO and building efficient heterojunction between ZnO and CdS.

Effect of Zn substitution on the AC induction heating properties of ZnxMn1-xFe2O4 (x = 0.1–0.9) nanoparticles prepared using microwave assisted synthesis

ZnxMn1-xFe2O4 (x = 0.1–0.9) magnetic nanoparticles (MNPs) were prepared using a microwave-assisted coprecipitation method, and the effect of Zn substitution on the AC induction heating properties of the MNPs was investigated. With increasing Zn substitution, owing to the lower solubility product of Zn2+ ions, the formation of new nuclei was preferred over grain growth, which reduced the average crystallite size. The saturation magnetization initially increased with Zn substitution, attained the maximum value at x = 0.5, and decreased beyond that due to Yafet-Kittel type triangular spin ordering. The prepared MNPs exhibited superparamagnetic behaviour at ∼ 300 K. AC induction heating studies of the MNPs indicated a specific absorption rate of ∼ 130 ± 4 W/gFe at x = 0.1. The AC induction heating efficiency did not exhibit any non-monotonic variation at x = 0.5, and progressively decreased with increasing Zn concentration. This was attributed to the reduction in the MNP size and anisotropy energy density at higher Zn concentration that caused the relaxation dynamics to be Nèel dominated with lower effective relaxation time. AC induction heating studies on the agar-immobilized samples confirmed the Brownian relaxation mediated magneto-thermal energy conversion at lower Zn concentration. The obtained results demonstrated that saturation magnetization alone does not influence the AC induction heating efficiency and relaxation dynamics play a significant role.

CoFe2O4@Methylcellulose/AC as a New, Green, and Eco-friendly Nano-magnetic adsorbent for removal of Reactive Red 198 from aqueous solution

• Methylcellulose (MC) was played an essential role to improve the nanomagnetic adsorbent structure for the Reactive Red 198 (RR198) adsorption. • CoFe 2 O 4 @MC/AC was synthesized as a novel nanomagnetic adsorbent with a facile, simple, and green microwave-assisted coprecipitation method. • The physical and chemical structure of CoFe 2 O 4 @MC/AC were approved with FTIR, FESEM, EDS, Mapping, Line Scan, XRD, VSM, and BET techniques. • The isotherm, kinetic and thermodynamic of RR198 adsorption were investigated. • CoFe 2 O 4 @MC/AC exhibited good chemical stability and reusability. Methylcellulose (MC) is the most common commercial cellulose ether and the most attractive biopolymer due to its cheap cost of biodegradability, biocompatibility, hydrophilicity, and lack of toxicity. In this study, CoFe 2 O 4 @MC/activated carbon (AC) was synthesized as a unique magnetic nano-adsorbent in the presence of MC biopolymer for Reactive Red 198 (RR198) dye removal. The nano-magnetic adsorbent was characterized by FESEM (Field emission scanning electron microscopy), EDS (Energy-dispersive X-ray spectroscopy), Mapping, Linescan, BET (Brunauer–Emmett–Teller), FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-Ray Diffraction), and VSM (Vibrating-Sample magnetometer). For simple separation by external magnetic fields, the Ms value was 57.91 emu/g. According to XRD analysis, the nano-adsorbent maintains its crystal structure, with an average crystal size of 11 nm. The maximum removal efficiencies of RR198 for synthetic and real wastewater samples under optimal conditions (an initial concentration of 10 mg/L, pH 3, contact time of 10 min, nanocomposite dose of 1.5 g/L, and a temperature of 25 °C) were 92.2% and 78%, respectively. The adsorption experiments were fitted well with the Freundlich isotherm (R 2 = 0.989) and pseudo -second-order kinetic (R 2 = 0.995). The values of entropy changes (ΔS = 35.087 kJ/mol.k), enthalpy changes (ΔH = -9.862 kJ/mol), and negative Gibbs free energy changes (ΔG) showed that the adsorption process was exothermic. Finally, the reusability findings showed that after six recovery cycles, the efficiency decreased slightly (90.1%). In the end, it can be concluded that the prepared CoFe 2 O 4 @Methylcellulose/AC can be used as an efficient adsorbent for the removal of RR198 from an aqueous solution.

Lattice defects and oxygen vacancies formulated ferromagnetic, luminescence, structural properties and band-gap tuning in Nd3+ substituted ZnO nanoparticles

ZnO and Zn1-xNdxO nanoparticles synthesized using the microwave assisted co-precipitation method were probed using XRD, HRTEM, UV–Vis spectroscopy, Raman spectroscopy, Photoluminescence spectroscopy and SQUID for robust and sufficient optical, structural, and magnetic profiles. The Hexagonal wurtzite structure of all the nanoparticles with a spherical shape and size in the 20-14 nm range was confirmed by XRD and HRTEM. The lower angle shift of the diffraction peaks indicated the interstitial addition of Nd3+ and collated to the lattice expansion. Urbach energy with its tail slope was used to define structural disorder in materials, and it increased with doping and decreased the optical band gap due to band-tail and tail-tail transitions. Broadening and asymmetry of the first-order E2 (high) phonon Raman mode identified structural disorder. The Spatial correlation model with changes in line center position, line width, and asymmetry of the E2 (high) phonon mode gave dopant created disorder. PL studies were used to determine the oxygen vacancy concentration, other defects, and excitation wavelength in all the nanoparticle samples that could be used as white light display devices. Magnetic studies with the BMP model were employed to confirm that Nd3+ doping leads to an increase in RTFM. Oxygen vacancies were considered to have a critical role in generating weak FM behavior in Zn1-xNdxO nanoparticles.

Structural, optical and electrical properties of copper oxide nanoparticles prepared through microwave assistance

Microwave assisted co-precipitation method is used to synthesize copper oxide nanoparticles from various concentrations of CuCl2.2H2O (0.1 M - 0.5 M) precursors. Both CuO and Cu2O phases are observed from X-ray diffraction (XRD) pattern and further confirmed from Energy Dispersive X-ray Analysis (EDX) and selected area electron diffraction (SAED) data. The particle size of 43 to 27 nm determined from XRD data using Scherrer formula is in good relation with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) images. The existence of reasonably uniform size and shape is clear from SEM. The band gaps determined from the UV-Visible absorption peaks and vibrational modes observed from Micro-Raman Scattering (MRS) analysis further confirm the presence of CuO and Cu2O phases. These results are also related to electrical conductivity at low temperatures which illustrate different types of conduction mechanisms. The samples show semiconducting behavior with improved electrical conductivity. Finally, the material is proposed to have applications in designing gas sensors and also in regulating electrical conductivity in drug delivery systems. Copyright © 2017 VBRI Press.

Preparation and evaluation of Ca/Mg-layered double hydroxide as a novel modifier for electrochemical determination of gibberellic acid

We report that Ca/Mg-layered double hydroxides (LDHs) were synthesized with the microwave-assisted co-precipitation method successfully. Ca/Mg-LDHs were used as new nanocomposites based on a glassy carbon electrode (GCE) for the determination of gibberellic acid (GA3). The electrochemical sensors were evaluated with Ca/Mg-layered double hydroxide (Ca/Mg-LDH) as a novel modifier. The high potential of the modified electrode to determine the low values of GA3 was studied by using DPV pulsed differential approach. Layered double hydroxides (LDHs) due to their unique and excellent physicochemical properties can be used in sensors based on glassy carbon electrode (GCE). The presence of LDHs in GCE improve the ratio of surface to volume and can increase accuracy and decrease the detection of limit. The final products were characterized by Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), Thermogravimetry (TG) and differential scanning calorimetry (DSC). The results showed that the LDH/GCE electrochemical sensor has good sensitivity for the determination of GA3 at a concentration range of 0.029 up to 0.297 mM, with the detection of limit about 0.009 mM.

Shrinkage Behavior, Thermal Expansion Behavior, and Electrical Conductivity Study of Samarium Doped Ceria Electrolytes

Ceria-based electrolytes generally have high sintering temperatures (~1500 °C)1,2, which increases the cell fabrication cost and decreases the mechanical stability of the cell due to rapid grain growth. In this work, the Ce0.9Sm0.1O2 (SDC) electrolyte is synthesized by microwave-assisted co-precipitation method using ethanol as a solvent. The sintering behavior of the green compact is studied using a dilatometer. Linear shrinkage and shrinkage rate behavior study shows a low sintering end temperature (1200 °C) and a final relative density of ~92%. A maximum linear shrinkage of -15.70% is observed at 1200 °C. A uni-modal shrinkage rate curve is seen, which confirms uni-modal pore size distribution in the powder. After 1388 °C, a dedensification is observed (+ 0.29% linear shrinkage), which might be associated with the reduction of Ce4+ to Ce3+ (please see Figure 1). Initial sintering results suggest that the synthesis method used has significantly lowered the SDC electrolyte's sintering temperature. Although the densification is completed at 1200 °C, the microstructure may change with further increase in the sintering temperature, affecting electrical conductivity. Inspired by the initial results, a detailed study on the effect of sintering temperature (1200 °C to 1500 °C) on the microstructure and electrical conductivity of SDC will be carried out and presented in the paper. S. Medisetti et al., Nano-Structures & Nano-Objects, 11, 7–12 (2017) https://www.sciencedirect.com/science/article/pii/S2352507X16301275.G. Accardo et al., J. Appl. Biomater. Funct. Mater., 14, 35–41 (2016) https://journals.sagepub.com/doi/abs/10.5301/jabfm.5000265. Figure 1