Cobalt Zinc Research Articles

Synthesis of porous ZnCo2O4 micro-cube with large tap density and its application in anode for lithium-ion battery

As high capacity anode materials, transition metal oxides show main shortage of poor cyclic stability. In this work, porous zinc cobaltate micro-cube was prepared by hydrothermal plus calcination process. At annealing temperature of 600 °C, the ZnCo2O4 displayed uniform particle size of ∼13 μm and large tap density of 2.4 g−1cm3. During electrochemical test, the material exhibited outstanding capacity retention of 93% (reversible charge capacity of 840 mAhg−1) after 200 cycles of charge/discharge process at 0.2 Ag‒1. Even over 1000 cycles at 1 Ag‒1, the charge capacity was still recorded as 588 mAhg−1 (much higher than 372 mAhg−1 of graphite anode), with retention of 76%. It could be demonstrated that the ZnCo2O4 porous cube expressed potential application prospect for anode materials of lithium-ion batteries.

Fabrication of (PS-Cr2O3/ ZnCoFe2O4) Nanocomposites and Studying their Dielectric and Fluorescence Properties for IR Sensors

In present work, study of dielectric and fluorescence properties of polystyrene (PS)- chromium oxide (Cr2O3) and polystyrene- chromium oxide doped by zinc cobalt iron oxides nanocomposites have been investigated. The samples have been prepared by adding ZnCoFe2O4 nanoparticles concentrations to the (PS-Cr2O3) nanocomposites by different weight percentages are (0, 2,4,6 and 8) wt.%. The results showed that the dielectric constant, dielectric loss and A.C electrical conductivity of (PS-Cr2O3) nanocomposites increase with an increase in ZnCoFe2O4 nanoparticles concentrations. The dielectric constant and dielectric loss decrease while the electrical conductivity increases with an increase in frequency. The results of dielectric and fluorescence properties showed that the (PS-Cr2O3/ZnCoFe2O4) nanocomposites can be used in different optoelectronics applications.

Functionalised microwave sensors for real-time monitoring of copper and zinc concentration in mining-impacted water

Microwave spectroscopy has been identified as a novel and inexpensive method for the monitoring of water pollutants. Integrating microwave sensors with developed coatings is a novel strategy to make the sensing system more specific for a target contaminant. This study describes the determination of copper and zinc concentration in water in both laboratory-prepared and acquired mine water samples from two abandoned mining areas in Wales, UK. Uncoated sensors immersed in samples spiked with 1.25 mg/L concentrations of copper and zinc, using the standard addition method, were able to quantify the concentration at 0.44 GHz with a strong linear correlation (R2 = 0.99) for the reflection coefficient magnitude (|S11|). Functionalised microwave sensors with l-cysteine, chitosan and bismuth zinc cobalt oxide-based coatings have shown improvement in the sensing performance. Specifically, the linear correlation at 0.91–1.00 GHz between |S11| and a polluted water sample spiked with Cu showed a higher (R2 = 0.98), sensitivity (1.65 ΔdB/mg/L) and quality factor (135) compared with uncoated sensors (R2 = 0.88, sensitivity of 0.82 ΔdB/mg/L and Q-factor 30.7). A Lorentzian peak fitting function was applied for performing advanced multiple peak analysis and identifying the changes in the resonant frequency peaks which are related to the change in metal ion content. This novel sensor platform offers the possibility of in situ monitoring of toxic metal concentrations in mining-impacted water, and multiple peak features, such as area, full width half maximum, centre and height of the peaks, have the possibility to offer higher specificity for similar toxic metals, as between copper and zinc ions.

Investigation of Strength and Cracking Behaviour of ZnCo2O4 Nanoparticles Incorporated Porous Concrete

In this study, the effect of limewater on strength assessments and percentage of water absorption of zinc cobaltate (ZnCo2O4) nanoparticles incorporated porous concrete has been investigated. Portland cement was partially replaced by ZnCo2O4 nanoparticles with the average particle size of 50 nm. The results indicated that the incorporation of nanoparticles could transform concrete with improved strength and water permeability when the specimens are cured in saturated water. The strength of concrete specimens without nanoparticles are relatively low compared to the specimen with ZnCo2O4 nanoparticles. The results show that the strengthening of nanoparticles incorporated specimens resulted from improved permeability together with high strength. Microstructure and morphology of the specimen after compressing test was observed by scanning electron microscopy (SEM). In addition, ZnCo2O4 nanoparticles are able to act as nanofillers and recovered the pore structure of the specimens by decreasing damaging pores.

Zinc Cobalt Layered Double Hydroxide Electrode for High-Performance Supercapacitor

Zinc Cobalt Layered Double Hydroxide Electrode for High-Performance Supercapacitor

Fabrication of bifunctional nanocomposite for dye degradation

An effective photocatalytic system is designed to treat with methylene blue. Graphene oxide matrix was decorated with cobalt ferrite and zinc oxide nanoparticles, providing it with dual functionality. The nanocomposite was prepared via sonochemistry. Structural characterization was done by X-ray diffraction. Morphology was observed by scanning electron microscopy while elemental analysis confirmed the purity of the synthesized nanocomposite. The photocatalytic activity of nanocomposite was tested for denaturing methylene blue under solar conditions. Enhanced photocatalytic activity was observed due to trapped electron-hole pairs at graphene oxide surface and other interfaces of the nanocomposite. The efficiency of photocatalyst was calculated as 98% within 15 min which was further examined till 5 more repeated cycles.

Investigation of sodium borohydride and hydrazine oxidation on gold nanoparticles modified zinc–cobalt coating

This work presents the investigation of the electrochemical oxidation of hydrazine and sodium borohydride ions in alkaline solutions on the Au nanoparticles modified ZnCo coating surface, which was deposited on the titanium substrate (termed as AuZnCo/Ti). The AuZnCo/Ti catalysts were prepared via a facile electrochemical deposition technique followed by a simple and low-cost galvanic displacement. Scanning electron microscopy, energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy were used for characterization of the prepared catalysts surface morphology, structure and composition, whereas their electrocatalytic behaviour was investigated for the electrochemical oxidation of hydrazine and sodium borohydride in an alkaline medium using cyclic voltammetry. It has been determined that the AuZnCo/Ti catalysts with Au loadings of 31, 63 and 306 µg cm–2 show enhanced catalytic activity towards the electrochemical oxidation of both hydrazine and sodium borohydride as compared to that of the ZnCo/Ti catalyst.

Electromagnetic and microwave absorption performance of Ni0.4Zn0.4Co0.2Fe2O4/polymethacrylimide foam synthesized via polymerization

In this paper, the effect of nickel–zinc–cobalt ferrite (NZCFO) content on the electromagnetic properties of polymethacrylimide (PMI)/NZCFO was studied. The functional nano-composite was successfully synthesized via novel suspension polymerization. Subsequently, the presence of functional groups and microstructure was investigated by Fourier transform-infrared spectroscopy and scanning electron microscopy, respectively. Based on electromagnetic analysis, it is found that the compressive strength and the entire X-band of the composite foam (thickness greater than 27 mm) reach to 2.6 MPa and an effective bandwidth (RL < − 10 dB) when the NZCFO content is 30 wt% of the reactive monomer. The analysis confirmed that the PMI/NZCFO (PMI/FO) foam composites enable the loss of an electromagnetic wave through the natural resonance effect of NZCFO. At the same time, the interwoven network structure and the cascade structure have a certain promotion effect on the loss of electromagnetic wave due to porous morphology of PMI foam. The synergetic effect of NZCFO and PMI shows the composite material owes significantly improved electromagnetic and microwave absorption performance.

Zinc Cobalt Sulfides on N, S Co-Doped Carbon Derived from Bimetallic-Organic Framework As an Advanced Electrocatalyst for Oxygen Reduction Reaction

Recently, the environmental problems caused by excess use of fossil fuels triggered intense research for efficient, inexpensive, and harmless energy conversion and storage devices such as fuel cells and rechargeable metal air batteries. In these applications, the oxygen reduction reaction (ORR) are a key electrochemical process for commercialization. Also, developing non-noble metal-based electrocatalysts with high electrochemical performance is very important in economic point of view. To address these issues, electrocatalysts based on nanocarbon frameworks such as metal organic frameworks (MOFs) and zeolitic imidazolate framework (ZIF) have been widely investigated as promising alternatives to Pt-based catalysts. In this work, we prepared bi-metallic ZIFs by coprecipitation of zinc and cobalt ions in the presence of 2-methylimidazole, followed by one-step sulfidation and carbonization to synthesize zinc cobalt sulfides supported on N, S co-doped porous carbon. The as-synthesized catalyst maintained inherent dodecahedral particle shape of ZIF. Furthermore, it exhibits outstanding ORR onset-potential (0.96 V vs. RHE) and half-wave potential (0.83 V vs. RHE), which is comparable to commercial Pt/C catalyst in alkaline electrolyte. Such outstanding electrochemical properties are mainly ascribed to the synergistic effect of the chemical composition, high electrochemical active surface area, and abundant active sites of the dodecahedral structure. These findings suggest that the transition metal sulfides on N, S co-doped porous carbon can be a promising alternative for the next generation of energy storage and conversion technologies.

Enhancing thermochemical energy storage density of magnesium‐manganese oxides

AbstractThree approaches for enhancing the energy density of magnesium‐manganese oxide porous reactive materials for thermochemical energy storage (TCES) are investigated: adjusting the mole ratio, lowering the oxygen partial pressure during thermal reduction, and transition metal oxide doping. The manganese‐to‐magnesium molar ratios are varied to determine the composition yielding maximal energy density. The increase in energy density by lowering the oxygen partial pressure during the reduction step is also studied. Volumetric oxygen exchange capacities are measured for every case considered. Finally, the effects of doping magnesium‐manganese oxide with cobalt oxide, iron oxide, zinc oxide, and nickel oxide on the TCES properties are examined. We found the optimal Mn/Mg ratio for maximum volumetric energy density is in the vicinity of 1/1, achieving 1813 ± 175, 2178 ± 204, and 2323 ± 281 MJ m−3 for oxygen partial pressures of 0.2, 0.05, and 0.01 atm during thermal reduction, respectively; lowering the oxygen partial pressure below atmospheric during thermal reduction enhances oxygen exchange capacities and improves the energy density between 10%‐42% and 24%‐55% for oxygen partial pressures of 0.05 and 0.01 atm, respectively, with the greatest increases observed for high manganese content samples; and, doped samples exhibit reduced oxygen exchange and questionable reactive stability, thus appearing to reduce energy density.

Enhanced magnetic and dielectric properties of doped Co–Zn ferrite nanoparticles by virtue of Cr3+ role

Chromium substituted cobalt zinc (Co0.8 − xZn0.2CrxFe2O4; (0 ≤ x≤0.1; step 0.02), referred to Co-Zn-Cr) nanoferrite materials were synthesized by citrate nitrate combustion method. The effect of Cr3+dopant on the crystal structure, magnetic properties, dielectric properties, electrical transport and impedance analysis of Co–Zn nanoferrites was predestined. The cubic spinel phase formation without any impurity phase for Co–Cr–Zn nanoferrites was assured by XRD, FTIR and HRTEM analysis. Magnetic parameters displayed a peculiar demeanor as a function of Cr content, based on the crystallite size impact. Dielectric phenomena versus frequency and temperature were discussed relying on charge carriers (electrons and holes) hopping between diverse ions. Complex impedance analysis revealed the entity of electrical relaxations in the investigated samples besides the predominant of grain boundaries contributions to the conduction process. A distinctive attitude for dielectric parameters was obtained with Cr dopant, regarding the cation–anion and cation–cation bond length. The nanoferrite Co0.72Zn0.2Cr0.08Fe2O4 has the optimum magnetic and dielectric properties, which qualifies it for recording media and high frequency devices.

Template agent for assisting in the synthesis of ZnCo2O4 on Ni foam for high-performance supercapacitors

Zinc cobalt oxide (ZnCo2O4) is successfully achieved by a simple hydrothermal process and adjusting the annealing temperature, utilizing sodium dodecyl sulfate (SDS), polyvinylpyrrolidone (PVP), cetyltrimethyl ammonium bromide (CTAB), and polyvinyl alcohol (PVA) as template agents. The prepared ZnCo2O4 exhibits a different morphological structure by adding a templating agent, which exhibits high capacitance and cycle stability. Specially, the ZnCo2O4 electrode using 1 g of PVP exhibited a superior performance with a high specific capacity of 1527.2 F g−1 at a current density of 1 A g−1 and 1204 F g−1 at 10 A g−1. In addition, P-ZCO was used as the positive electrode, and activated carbon (AC) was used as the negative electrode to assemble an asymmetric supercapacitor device. It has an energy density of 69.2 Wh kg−1 at a power density of 774.6 W kg−1, and a retention rate of 77% at a current density of 10 A g−1, which exhibits excellent performance.

Synthesis of Magnetic Ferrite Nanoparticles with High Hyperthermia Performance via a Controlled Co-Precipitation Method.

Magnetic nanoparticles (MNPs) that exhibit high specific loss power (SLP) at lower metal content are highly desirable for hyperthermia applications. The conventional co-precipitation process has been widely employed for the synthesis of magnetic nanoparticles. However, their hyperthermia performance is often insufficient, which is considered as the main challenge to the development of practicable cancer treatments. In particular, ferrite MNPs have unique properties, such as a strong magnetocrystalline anisotropy, high coercivity, and moderate saturation magnetization, however their hyperthermia performance needs to be further improved. In this study, cobalt ferrite (CoFe2O4) and zinc cobalt ferrite nanoparticles (ZnCoFe2O4) were prepared to achieve high SLP values by modifying the conventional co-precipitation method. Our modified method, which allows for precursor material compositions (molar ratio of Fe+3:Fe+2:Co+2/Zn+2 of 3:2:1), is a simple, environmentally friendly, and low temperature process carried out in air at a maximum temperature of 60 °C, without the need for oxidizing or coating agents. The particles produced were characterized using multiple techniques, such as X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV–Vis spectroscopy), and a vibrating sample magnetometer (VSM). SLP values of the prepared nanoparticles were carefully evaluated as a function of time, magnetic field strength (30, 40, and 50 kA m−1), and the viscosity of the medium (water and glycerol), and compared to commercial magnetic nanoparticle materials under the same conditions. The cytotoxicity of the prepared nanoparticles by in vitro culture with NIH-3T3 fibroblasts exhibited good cytocompatibility up to 0.5 mg/mL. The safety limit of magnetic field parameters for SLP was tested. It did not exceed the 5 × 109 Am−1 s−1 threshold. A saturation temperature of 45 °C could be achieved. These nanoparticles, with minimal metal content, can ideally be used for in vivo hyperthermia applications, such as cancer treatments.

Effect of Y3+, Sm3+ and Dy3+ ions on the microstructure, morphology, optical and magnetic properties NiCoZn magnetic nanoparticles

Nano-sized magnetic particles of Yttrium, Samarium, and Dysprosium doped Nickel Cobalt Zinc were successfully synthesized by the sol-gel auto-combustion technique in order to investigate different structural, morphological, elemental, optical and magnetic properties with the usage of different characterization techniques. The characterization techniques used for studying different properties of synthesized samples were XRD, FESEM, EDS, FTIR, and VSM. The XRD patterns revealed the formation of single-phase inverse spinel cubic structure with an average crystallite size (D) in the range of 59–63 nm. The surface morphology of the synthesized samples carried out by FESEM surely indicates the formation of dense, cubic in shape and agglomerated magnetic nanoparticles. The EDS spectra of prepared samples show the formation of pure magnetic nanoparticles. The Fourier infrared transform spectroscopy supports our XRD results to a great extent that the synthesized magnetic nanoparticles have single-phase inverse spinel cubic structure by giving the spectrum in the range of 419–594 cm−1. The magnetic measurements were carried out by Vibrating Sample Magnetometer for calculating different magnetic parameters such as saturation magnetization (Ms), coercivity (Hc), remanent magnetization (Hc) and magnetic moment (nB) which was found to be in the range of 54–63 emu/g, 34–209 Oe, 1.99–19.89 emu/g and 2.29–2.66. The magnetic analysis of synthesized samples has been explained on the basis of the theory of exchange interactions and Neel's sublattice model.

Elemental metabolomics to identify pregnancy risk factors and predict gestational outcomes

Objectives: Micronutrition is associated with a range of perinatal outcomes and risk factors known to cause gestational disorders. Asthma, BMI, and smoking have all shown to have significant effects on pregnancy outcomes such as preterm birth, and small for gestational age (SGA). This project aims to apply elemental metabolomics in plasma and urine to identify relationships between elemental concentrations and pregnancy risk factors, using this information to predict gestational outcomes. Methods: Plasma and urine samples were obtained from a cohort of 18-week pregnant women from the Lyell McEwin Hospital (Adelaide, Australia). Inductively coupled plasma mass spectrometry was used to measure 29 elements in plasma and urine from 117 patients (69 control, 48 complicated). Results: High BMI was associated with lower concentrations of essential elements magnesium, iron, and selenium in both plasma and urine (8.5% - 27%, p < 0.05) and higher concentrations of plasma copper (12%, p < 0.01). Asthmatic patients had increased levels of plasma sodium (5.9%, p < 0.05); whilst cobalt, cadmium, and caesium were lower, along with urinary manganese (24% - 81%, p < 0.05). Smoking was associated with higher urinary zinc, rubidium, and plasma cobalt (24% - 43%, p < 0.05). Using receiver operating characteristic curves, placental weight, SGA, and preterm birth were able to be detected at 18 weeks. Increased selenium and molybdenum in plasma predicted a placenta under 500 g with 89% accuracy. Babies born SGA were identified 88% of the time using the ratio of copper to strontium in plasma. In 80% of cases, urine thallium and iodine could distinguish preterm birth from term pregnancies. Conclusion: This study is the first to apply elemental metabolomics to multiple samples from 18-week pregnant women. The power of elemental metabolomics can be seen in its ability to possibly predict gestational outcomes early, providing insight into these complex disorders and risk factors.

Structural and magnetic properties of nanosized CoxZn(1-x)Fe2O4 (x= 0.0, 0.5, 1.0) synthesized via autocatalytic thermal decomposition of hydrazinated cobalt zinc ferrous succinate

Nanocrystalline monophasic cobalt substituted zinc ferrite with general formula CoxZn(1-x)Fe2O4 (x = 0.0, 0.5, 1.0) were synthesized by precursor combustion method. The precursors namely, hexa-hydrazine cobalt zinc ferrous succinate with formulae CoxZn(1-x)Fe2(C4H4O4)3.6N2H4 (x = 0.0, 0.5, 1.0) were characterized by IR, CHNS, ICP-AES analysis, and their thermal studies were carried out by TG-DTA, TG-DTG, and isothermal mass loss studies. The ‘as prepared’ Co–Zn ferrites obtained by auto-catalytic thermal decomposition of precursors, on initial ignition, were characterized by XRD, IR, EDAX, TEM, and SEM. The SAED and XRD studies confirmed the formation of crystalline single phase nano Co–Zn ferrites. The morphology of these ‘as prepared’ ferrites was studies by TEM analysis which confirmed the particles to be in the nanometer range (20–30 nm). The increase in cobalt concentration resulted in reduced lattice parameter. The electrical resistivity declined while the Curie temperature surged with a decreased zinc concentration in ‘as prepared’ Co–Zn ferrites. The magnetization studies with the applied field at 300 K and 50 K displayed a gradual increase in magnetization values with the rise in cobalt content while confirming the super-paramagnetic nature of Co–Zn ferrite nano-system.

Hierarchical zinc cobalt sulfide flowers grown on nickel foam as binder-free electrodes for high-performance asymmetric supercapacitors

In this work, hierarchical zinc cobalt sulfide flowers on nickel foam (f-Zn0.76Co0.24S/Ni foam) are fabricated by a facile two-step hydrothermal method. The obtained f-Zn0.76Co0.24S/Ni foam are directly used as the binder-free electrodes for high-performance supercapacitors. The as-prepared f-Zn0.76Co0.24S/Ni foam exhibite a high specific capacitance of 1906 F g−1 at a current density of 1 A g−1 and good rate performance. The excellent electrochemical performance can be attributed to the unique interconnected flower structure, which provides a path for the rapid diffusion of electrolyte ions. Moreover, the f-Zn0.76Co0.24S/Ni foam//Fe2O3@rGO asymmetric supercapacitor is assembled. It can achieve a high energy density of 75.7 Wh kg−1 at a power density of 700.5 W kg−1 and display superior cycling stability with 86.7% retention after 8000 cycles.

Zinc cobalt sulfide nanoparticles as high performance electrode material for asymmetric supercapacitor

Zinc cobalt sulfide (ZCS) is a promising and high performance electrode material for pseudocapacitors due to its good electrical conductivity, abundant active sites and rich valence states. In this work, zinc cobalt oxide (ZCO) nanoparticles are firstly synthesized via a hydrothermal method assisted by hexadecyltrimethyl ammonium bromide (CTAB), and then transformed into zinc cobalt sulfide nanoparticles (ZCS NPs) using a facile sulfuration process. The average diameter of ZCS NPs is estimated to be about 15 nm, which is beneficial for Faradaic redox reactions in energy storage process due to their numerous active surfaces. The ZCS NPs are then coated onto a nickel foam to form the working electrode of supercapacitors. Because the ZCS electrode has lower series and charge transfer resistance, and also higher ion diffusion rate than that of the ZCO electrode, it achieves a large specific capacitance of 1269.1 F g−1 at 0.5 A g−1 in 2 M KOH electrolyte, which is four times more than that of the ZCO electrode (e.g., 295.8 F g−1 at 0.5 A g−1). In addition, an asymmetric supercapacitor using the ZCS NPs as the positive electrode and activated carbon as the negative electrode is assembled, which delivers a high energy density of 45.4 Wh kg−1 at a power density of 805.0 W kg−1, with an excellent cycling stability (91.6% retention of the initial capacitance over 5000 cycles).

Room temperature ac conductivity, dielectric properties and impedance analysis of polypyrrole-zinc cobalt oxide (PPy/ZCO) composites

Zinc-cobalt oxide nanoparticles were fabricated by hydrothermal method. The polypyrrole and zinc cobalt oxide (PPy/ZCO) composites were synthesized by using in-situ chemical polymerization method. These composites were characterized by x-ray diffraction (XRD) which confirmed the crystalline nature of the PPy/ZCO composites. The scanning electron microscopy and energy dispersive x-ray diffraction (EDX) confirmed the spherical structured particles of composites and the chemical composition, respectively. Electrical characterizations of PPy/ZCO composites were analyzed as a function of ZCO concentration in the frequency range of 102–106 Hz. The alternating current (ac) conductivity versus frequency graph for PPy/ZCO composites showed a direct current (dc) plateau in the frequency range of 102–104 Hz, indicating an isolated network within the composites. At the higher frequencies, there was an increase in ac conductivity obeying the universal dynamic response (UDR). The UDR suggested that the conduction in the PPy/ZCO composites was due to hopping along the polymer chains due to filler nanoparticles. The nature of response of real and imaginary part of impedance (Nyquist plot) revealed that the conduction has attribution from the effects of grains and grain boundaries.

Fabrication and characterization of Intermediate-Temperature Solid Oxide Fuel Cell (IT-SOFC) single cell using Indonesia’s resources

Solid Oxide Fuel Cell (SOFC) is one of the promising developments in the fuel cell system. SOFC can be applied to micro-scale combined heat and power generation (micro CHP) as a power plant in housing. Recently, intermediate-temperature SOFC (500-700°C) is being widely developed since cheaper than the conventional SOFC (∼1000°C). Intermediate-temperature and conventional SOFC are less developed in Indonesia due to expensive electrode and electrolyte materials, such as Yttria and Lanthanum, which are not available in Indonesia. This study aims to develop a novel disk-shaped single cell SOFC based on materials from Indonesia’s resources. Calcia Cobalt Zinc Oxide (CCZO) is an alternative cathode to replace conventional cathode such as Lanthanum Strontium Manganite (LSM). CCZO cathode was made using spray coating. Calcia can also substitute Ytrria as a stabilizer of zirconia in electrolyte fabrication. Calcia-stabilized Zirconia (CSZ) electrolyte was produced using spray coating. NiO anode was fabricated through hydraulic pressing. The single cell was operated using hydrogen (125 sccm) as a fuel and ambient air (500 sccm) as an oxidant. The results showed an open-circuit voltage (OCV) of 0.577, 0.558, and 0.513 V and produced the maximum power densities of 1.4, 2.8, and 10 mW m−2 at 500, 600, and 700°C, respectively. Measurement of the cell impedance indicated that the overall resistance decreased with increasing temperature.