Increasing Cobalt Content Research Articles

Study of the impregnation sequence of active phase and effect of cobalt content over Co-CeO2/MgΑl2O4 catalysts in ethanol steam reforming

Co–CeO2/MgAl2O4 catalysts were obtained by varying the impregnation order (sequential or co‒impregnation) of active phase (Co) and Ce and were evaluated in the ethanol steam reforming (ESR) reaction. Results from TPR and XPS revealed that the impregnation order influenced the metal‒metal and/or metal‒support interactions and Co0/Con+, Ce3+/Ce4+ and the Co/Ce surface molar ratio, affecting the catalyst behavior in the ESR reaction. The solids prepared by sequential impregnation, Co/Ce/S and Ce/Co/S exhibited a greater degree of reduction than the solid obtained by co‒impregnation (CoCe/S), though these systems displayed low dispersion of Co species and low content of surface Co°. The solid CoCe/S showed the highest dispersion (68.5%) and greater presence of Co0 on the surface. The effect of the cobalt content (4, 8 and 12 wt%) was also examined in catalysts prepared using the co‒impregnation method. With the increase in cobalt content, a greater loss of stability and a greater amount of carbon deposits were observed. The highest H2 yield (5.3 mol H2/mol C2H5OH) and stability were achieved over the solid obtained by co‒impregnation with 8 wt% Co, which was attributed to the high dispersion of the active phase and its high content of surface metallic cobalt.

Fabrication And Studies Of structural, Dielectrical Properties Of (Ni0.95-xCoxCu0.05Fe2O4) Composites by Powder Technology Method

In this paper, the preparation of compounds, Ni0.95CoxCu0.05Fe2O4) by using powder technology method where (X = 0, 0.01, 0.02, 0.03, 0.04,and 0.05) annealing at 1100 C temperature for four hours. A series of samples were carried out for the study of structural properties by measuring x-ray diffraction (XRD). It included the study of the lattice constant (a), the particle size (D), the porosity (P) and the virtual density by x-ray diffraction, (x-ray density) as well as the study of Dielectric properties using the LCR , the study of the loss of dielectric meter tand and the electric conductivity (Ϭac). The results of X-ray diffraction showed that all samples had a crystalline,) and also showed that the Lattice constant (a) increases as the content of cobalt increases the density of the particles calculated by X-ray diffraction increases with the cobalt content, while the porosity and particles size decreases as the cobalt content increases, and the electrical show that the real and imaginary dielectric and electrical conductivity using current decreases as frequency increases, the real electrical dielectric constant increases as the cobalt content increases, while the imaginary part of dielectric constant and electrical conductivity decreases as the cobalt content increases.

Ductility reduction upon cobalt substitution in B2 NiTi

This paper reports the effect of ternary addition of cobalt to B2 NiTi by varying concentrations × = 0.125, 0.25 and 0.375 in Ni0.5−xCoxTi0.5 and the impact on their crystal structure, electronic and mechanical properties using first-principles calculations. The third element Co was substituted on both Ni and Ti sub-lattices using the supercell approach, site preference energy and formation energy suggest the preference of Co substitution on Ni sub-lattice agreeing with literature. The evolution of the electronic and mechanical properties from undoped NiTi to TiCo by substitution of Ni by Co is hereby discussed. Young’s (E) and shear (G) modulus is found to gradually increase as concentration (x) is increased. Importantly, ductility decreases with increasing cobalt concentration. From DOS, it is observed that the delocalized d states are reduced upon increasing Co addition due to strong d-d hybridization which reduces the metallicity and in turn ductility. This increase in Young’s modulus and decrease in ductility upon cobalt addition is indicative of the overall stiffness and resistance to deformation.

Solvothermal synthesis of magnetically separable Co–ZnO nanowires for visible light driven photocatalytic applications

Magnetically retrievable Cobalt doped ZnO nanowires were synthesised by simple solvothermal method. The prepared Co–ZnO nanowires were analysed with several characterization instruments such as FESEM, XRD, FTIR, VSM, UV–vis spectroscopy, XPS and PL spectroscopy. No other phase has been identified besides wurtzite phase, according to the structural analysis of pure ZnO and Co–ZnO nanowires. As the concentration of Co doping increased, ZnO nanowires' band gap energy dropped. Moreover, ZnO's absorption peak has a minor wavelength shift toward longer wavelengths. Green light emission was detected by PL analysis of ZnO nanowires and also the PL intensity of ZnO nanowires was decreased after cobalt doping. Co–ZnO nanowires exhibited ferromagnetic property. The coercivity and retentivity of Co–ZnO nanowires were increased with increase of Cobalt concentration. Improved visible light photocatalytic activity for the breakdown of methyl orange dye was achieved by Co–ZnO nanowires.

Cobalt-Copper Oxide Catalysts for VOC Abatement: Effect of Co:Cu Ratio on Performance in Ethanol Oxidation

The effect of the Co-Cu oxide catalysts composition on their physicochemical properties and performance in the deep oxidation of ethanol was studied. The catalysts with Co:Cu molar ratios of 4:1, 1:1, and 1:4 were obtained by calcination (4 h at 500 °C in air) of the coprecipitated precursors and characterized in detail using powder XRD, Raman spectroscopy, N2 physisorption, H2-TPR, and XPS. The powder XRD and Raman spectroscopy indicated the formation of Co3O4 and CuO mixtures rather than Co-Cu mixed oxides. The CuO promoted the Co3O4 reduction; the Co-Cu catalysts were reduced more easily than the single-component Co and Cu oxides and the main reduction maxima were shifted to lower temperatures with increasing cobalt content in the catalysts. The Co-Cu oxide catalyst with a Co:Cu molar ratio of 4:1 exhibited the best performance in ethanol gas-phase oxidation, showing the lowest T50 (91 °C) and T90(CO2) (159 °C) temperatures needed for 50% ethanol conversion and 90% conversion to CO2, respectively. The excellent catalytic properties of this Co-Cu oxide catalyst were ascribed to the synergistic effect of Co and Cu components. The high activity and selectivity of the Co-Cu catalyst was attributed to the presence of finely dispersed CuO particles on the surface of Co3O4.

Aluminum Deoxidation Equilibrium in Molten Fe-Co Alloys

Aluminum deoxidation equilibrium of molten Fe-Co alloy was experimentally measured using a chemical equilibrium method and numerically assessed using a sub-regular solution model based on Darken’s quadratic formalism and a Redlich-Kister type polynomial at 1873 K. It was found that the degree of oxygen content reduction by Al-deoxidation decreased with increasing cobalt concentration in the alloy, peaking at around 40 to 60 mass% Co, and then improved with further increase in cobalt concentration. The following binary interaction parameters between cobalt and aluminum were derived in this study:

Microwave absorption characteristics of cobalt doped zinc spinel ferrites in Ku-band (12.4–18 GHz)

This research study targets to fabricate microwave absorbers with narrow sample thickness, strong absorption power and broad bandwidth simultaneously. The zinc-cobalt spinel ferrites with compositional formula Zn1-xCoxFe2O4 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) are successfully synthesized via sol–gel citrate route by sintering at 1000 °C. Vector network analyzer is employed to determine dielectric permittivity εr=ε′-jε" and magnetic permeability μr=μ′-jμ" in Ku-band. Enhancement in dielectric losses from 0.3051 to 0.4066 and magnetic losses from 0.0087 to 0.5911 with increasing cobalt concentration from x = 0.00 to x = 1.00 at 12.4 GHz frequency helps in achieving good absorption. Normalized wave impedance and quarter wavelength model are used to maximize absorption or minimize reflection. Significant absorption is achieved by tuning thickness of the sample from 1.8 mm to 3 mm. The composition x = 0.75 exhibits superior absorbing properties by showing reflection loss as low as −31.45 dB along with −10 dB bandwidth of 5.6 GHz at a matching thickness of 2.2 mm. The fabricated ferrite samples are proved to be promising applicants for absorption of electromagnetic interference (EMI) in radar and stealth technology.

Spatiotemporal Design of the Metal-Organic Framework DUT-8(M).

Switchable metal-organic frameworks (MOFs) change their structure in time and selectively open their pores adsorbing guest molecules, leading to highly selective separation, pressure amplification, sensing, and actuation applications. The 3D engineering of MOFs has reached a high level of maturity, but spatiotemporal evolution opens a new perspective toward engineering materials in the 4th dimension (time) by t-axis design, in essence exploiting the deliberate tuning of activation barriers. This work demonstrates the first example in which an explicit temporal engineering of a switchable MOF (DUT-8, [M1 M2 (2,6-ndc)2 dabco]n , 2,6-ndc = 2,6-naphthalene dicarboxylate, dabco = 1,4diazabicyclo[2.2.2]octane, M1 = Ni, M2 = Co) is presented. The temporal response is deliberately tuned by variations in cobalt content. A spectrum of advanced analytical methods is presented for analyzing the switching kinetics stimulated by vapor adsorption using insitu time-resolved techniques ranging from ensemble adsorption and advanced synchrotron X-ray diffraction experiments to individual crystal analysis. A novel analysis technique based on microscopic observation of individual crystals in a microfluidic channel reveals the lowest limit for adsorption switching reported so far. Differences in the spatiotemporal response of crystal ensembles originate from an induction time that varies statistically and widens characteristically with increasing cobalt content reflecting increasing activation barriers.

Improved Electrical Properties of Strontium Hexaferrite Nanoparticles by Co2+ Substitutions.

In this work, the sol-gel route was employed to synthesize a series of Co2+-substituted strontium hexaferrite nanoparticles (Sr1-x Co x Fe12O19, x = 0.0-0.50) to study the effect of cobalt ions doping on the magnetic, electrical, and structural properties of the nanoparticles. The structural analysis of the synthesized nanoparticles, performed by X-ray diffraction, showed the formation of a hexagonal structure having no secondary phases. The morphological analysis, performed through scanning electron microscopy, revealed spherical shaped nanoparticles with uniform distribution. Fourier transform infrared spectra demonstrated two consistent absorption bands indicating the intrinsic stretching vibrations around 600 and 400 cm-1 for tetrahedral and octahedral sites, respectively. It was observed through VSM that with cobalt addition, the saturation magnetization increased and the coercivity decreased. Also, a typical decreasing trend of DC electrical resistivity with increasing temperature measured by a two-probe method confirmed the semiconducting behavior of the synthesized samples. An impedance analyzer was used for the dielectric measurements at room temperature against the alternating frequency range of 250 Hz to 5 MHz, and it was found that the dielectric constant decreased with the increase in cobalt content, suggesting that the doped nanomaterials can be used for microwave absorption, electronics, telecommunication, and other high-frequency applications.

Enhancement of opto-electrical properties in Co doped CdS–TiO2 nanocomposite thin film as photoanode for Semiconductor Sensitized Solar Cells (SSSCs)

Cobalt doped CdS–TiO 2 nanocomposite thin films were coated on glass substrates by bottom up approaching methods. ZnS nanolayer over cobalt doped CdS–TiO 2 films act as a protective layer of CdS nanocrystal which enhances the photo stability. The structural, optical, electrical and surface morphological properties of ZnS-cobalt CdS–TiO 2 composite thin film were systematically evaluated. Structural analysis indicates that Co 2+ ions have been successfully incorporated in CdS site. The doping of cobalt in ZnS–CdS–TiO 2 film gives rise to an increase in the lattice parameter while the band gap decreased with increasing cobalt concentration. The bandgap of doped film decreases indicating the easy way of electron transfer from valence band to conduction band of CdS and TiO 2 . Surface morphological studies shows the diffusion of cobalt doped CdS nanoparticles into TiO 2 nanoporous structure of the composite film . The emission peaks in photoluminescence spectrum of ZnS-cobalt CdS–TiO 2 film proved the clear interaction of cobalt dopant with CdS nanocrystals. An enhancement in conductivity was observed due to incorporation of cobalt in CdS site and the resistance value (∼47%) was significantly decreased for cobalt doped CdS under illumination condition. Electrical analysis proved that the doped film is preferred as conductive electrode in solar cells than undoped film. • Cobalt doped CdS–TiO 2 composite thin films were synthesized by simple wet chemical method. • Interlocked CdS nanocrystals observed in SEM analysis, facilitate easy penetration into TiO 2 nanoporous structure of the composite film. • The doped film exhibit shifting of absorption edge towards longer wavelength (red shift), indicates decreased optical band gap. • The doped film shows superior electrical performance due to decreased resistance, preferred as conductive electrode in solar cells.

Effect of cobalt substitution in Zn1-xCoxFeCrO4 ferri-chromate: emerging light absorber for degradation of model textile dye

The concentration (x = 0.0 to 1.0) of cobalt doped magnetically separable Zn1-xCoxFeCrO4 ferrite was produced by sol-gel auto combustion utilizing glycine as a fuel. We can deduce that a single-phase cubic spinel system is synthesized based on powder XRD measurements and Rietveld refinement of the Zn1-xCoxFeCrO4 ferrite system. With the increase in cobalt content in the Zn1-xCoxFeCrO4 ferrite system, morphological examination revealed irregularly formed nanostructures ranging in size from 10 nm to 40 nm. When this ferrite system was exposed to TEM examination, similar morphological results were found. The coercivity of the Zn1-xCoxFeCrO4 ferrite system increased as the density and crystallite size were reduced. The remanence ratio rises in proportion to the increase in cobalt content. The visible region's optical characteristics were studied, and a blue shift in the band gap was observed with the increase in concentration of cobalt. The photo catalytic activity of as-synthesized Zn1-xCoxFeCrO4 ferrites on methylene blue (MB) dye degradation was evaluated because the band gap of the catalysts lies in the visible region. Within 85 minutes, the targeted photocatalyst degraded 96.7% of methylene blue, equating to a high degradation reaction rate constant k value up to 0.0089 min−1. As a result, the catalyst has a bright future in terms of environmental remediation. Increased photo catalytic activity is attributed to inhibition of load carrier separation due to crystallinity, proper band energy structure, and morphology of Co2+ doped Zn1-xCoxFeCrO4 ferrite. In addition, our targeted photo catalyst Zn0.25Co0.75FeCrO4 showed good stability and radical scavenger tests suggesting that holes/ hydroxyl radicals were the primary components for increased activity.

Tailoring the Magnetic and Optical properties of MgO Nanoparticles by Cobalt doping

In this work, Cobalt (0-10) % doped MgO nanoparticles are prepared for magnetic and optical studies. X-ray diffraction studies show the particle size increases from 3.10 nm to 9.50 nm with increasing Cobalt concentration in MgO samples. The secondary phases are observed beyond 5% Cobalt in the host MgO which indicates the solubility limit of dopant in this material. SEM analysis further reconfirms the purity and spherical morphology of nanoparticles in all samples. Its result also reveals that the smallest particles have the largest oxygen vacancy concentration as compared to other samples. The dopant and size-induced effects are observed for electronic absorption spectra and bandgap of the samples. UV-visible absorption spectra show a quantum confinement effect as the optical band gap decreases with the increase of the particle size. The optical band gap of the nanoparticles ranges from 4.68 eV to 3.15 eV which is very less in comparison with the bulk MgO band gap up to 7.2eV. Vibrating sample magnetometer studies at room temperature clearly show the ferromagnetic behavior for pure MgO nanoparticles in contrast with the paramagnetic behavior for other samples. It is suggested that the presence of the ferromagnetic behavior in pure MgO nanoparticles are due to the presence of oxygen vacancies.

Mechanical properties and magnetic properties of in-situ Co3Fe7 reinforced YCF102 coating by laser cladding

The effect of in-situ Co3Fe7 particles formed by laser cladding on the mechanical properties and magnetic properties of coatings are investigated. YCF102 alloy powder is selected and mixed with different content of cobalt, and each mixed powder is laser cladded on the AISI1045 substrate. The main phase composition of coating with different cobalt content are revealed. The microhardness and wear resistance of each sample are analyzed, and the wear mechanism of each sample are researched. Meanwhile, the magnetic properties of each sample are analyzed and researched. The results show that Co3Fe7 particles are formed in-situ in the YCF102 coating with different cobalt content, and the microhardness and average friction coefficient do not change monotonously with the increase of cobalt content. When the cobalt content is 10wt%, the coating has excellent mechanical properties. In addition, due to the appearance of soft magnetic phase Co3Fe7 and grain size effect, the saturation magnetization and initial permeability present a tendency to first decrease and then increase, and the coercivity shows a trend of increasing and then decreasing.

Efficacy of surface-functionalized Mg1-x Co x Fe2O4 (0 ≤ x ≤ 1; Δx = 0.1) for hyperthermia and in vivo MR imaging as a contrast agent.

Surface-functionalized Mg1−xCoxFe2O4 (0 ≤ x ≤ 1; Δx = 0.1) can be an exciting candidate as an MRI contrast agent and for thermotherapeutic applications. The figure-of-merit, T2, relaxivity, r2, of MRI and specific loss power, SLP, of hyperthermia depend on the structural and magnetic properties of the nanoparticles. We synthesized cobalt-substituted magnesium ferrite Mg1−xCoxFe2O4 (0 ≤ x ≤ 1 with Δx = 0.1) nanoparticles using a chemical co-precipitation method. The lattice parameter and average crystallite size increase with the increase in cobalt content. The force-constant of FTIR of the tetrahedral sites increases, and that of the octahedral sites decreases with an increase in cobalt content. The room temperature Mössbauer spectra of Mg1−xCoxFe2O4 show that the Mössbauer absorption area of the A site decreases, and the Mössbauer absorption area of the B site increases with x. The Mössbauer spectra and M–H hysteresis loops at room temperature confirmed that a transition from fast relaxation (superparamagnetic) to mixed slow/fast (superparamagnetic/ferrimagnetic) relaxation occurs with changing cobalt content. The cobalt ion tends to occupy the octahedral B site, which makes the A–B interaction stronger; therefore, we see the above transition. Cytotoxicity experiments on HeLa cells revealed that both chitosan and chitosan-coated magnesium cobalt ferrite nanoparticles are biocompatible. In the Mg1−xCoxFe2O4 series, both r2 and SLP increase with x because of the increase in magnetization and anisotropy.

Validation of different tungsten carbide-cobalt grades as tool electrode material for sinking EDM

In sinking electrical discharge machining (EDM), tool electrode wear is crucial for an economical production. The tool electrode wear affects the process efficiency and determines the number of required tool electrodes for a specific machining process. Therefore, the relative tool wear, describing the relation of removed material volume between tool and workpiece electrode, needs to be minimised. The tool wear characteristics in sinking EDM depend strongly on EDM processing parameters and the applied electrode materials. Especially in micro-EDM, a significant increase of relative tool wear is representative. Because of its thermophysical properties tungsten carbide-cobalt (WC-Co) is a suitable material for the application as sinking EDM tool electrode. The economical production of WC-Co form electrodes for EDM sinking is enabled by recent advancements in precision milling of hard materials.Due to non-existent research on which composition of WC-Co is most advantageous for the application as sinking EDM tool electrode material, previous investigations have been intensified to describe correlations between material properties, EDM processing parameters and EDM processing results concerning material removal rate and relative tool wear. Therefore, various WC-Co grades with differing grain size and cobalt content were analysed in sinking EDM experimental studies. It was observed that the factor grain size showed an ambiguous effect concerning the process results. An increasing cobalt content led to a reduction of relative tool wear, which can be explained by the microstructure of the cobalt binder phase with its higher electrical conductivity. The WC-Co grades with beneficial EDM processing results have been further investigated in EDM parameter studies with differing tool electrode geometries. The experimental results concerning relative tool wear, with a minimum of 3 % for macro- and 5 % for micro-sized geometries, proved the suitability of specific WC-Co compositions as tool electrode material for sinking EDM.

The Influence of cobalt concentration in nutrient medium on growth of California worm biomass and metal accumulation in it

The biomass of the California redworm hybridis abiologically valuable feed additive for farm animals, poultryand fish. Worms contain a large amount of protein, lipids,vitamins and trace elements. The chemical composition ofworm biomass depends on the nutrient medium on whichit was grown. Worms are able to accumulate trace elementsfrom the nutrient medium in their body. Using this property,we conducted research on the biomass of worms enrichedwith Cobalt with the prospect of its furthe rusein fishfeeding. It was found that increasing the number and weightof worms depends on the content of Cobalt in the nutrientmedium. The in troduction of 20 mg/kg of Cobalt in to thenutrient medium increased the number and weight of wormsweighing 0.4-0.8 g, respectively, by 38.0% and 40.4%. Anincrease in the number of immature worms by 32.2% wasdetected. By adding 40 mg/kg of Cobalt to the nutrientmedium, the umber and weight of worms increase by 45.9and 51.1%, respectively. The introduction of Cobalt in theamount of 160 mg/kg resulted in a decrease in the numberof worms weighing 0.4-0.8 g compared to the experimentalgroups by 6.5-27.7%. It was found that at a dose of Cobalt160 mg/kg, the number of small worms decreased relativeto the experimental groups by 24.0-50.7%. There was adecrease and weight of young worms relative to control by22.4%.It is established that with increasing cobalt content in thenutrient medium increases its concentration in the biomassof worms. The highest content of Cobalt was found in thedrymatter of the biomass of worms grown on a nutrientmedium to which was added the test metalin the amount of160 mg/kg.The biomass of worms grown on a nutrient medium towhich was added 40 mg/kg of the investigated metal canbeuse das a protein supplement with high cobalt content infish feeding. Key words: vermiculture, wormbiomass, metalaccumulation, nutrient medium, Cobalt, atomicabs orptionspectros copy.

Effect of Co concentration and temperature on the energy transfer process between Mn2+ and Co2+ ions in Zn0.99-xMn0.01CoxTe nanocrystals

In this paper, we report a P2O5 – ZnO – Al2O3 – BaO – PbO glass system study, nanostructured with Zn0.99-xMn0.01CoxTe nanocrystals (NCs), synthesized by a fusion method. Transmission electron microscopy (TEM) images confirm the formation and electron paramagnetic resonance (EPR) spectra confirm the substitutional incorporation of Mn2+ and Co2+ ions in these NCs. The overlap between the Mn2+ ion emission bands and the Co2+ ion absorption bands suggests that an efficient resonance energy transfer from Mn2+ to Co2+ ions can be expected in these NCs. Indeed, the increase in emission intensity of Co2+ ions and the decrease in emission intensity of Mn2+ ions, as well as the decrease in lifetime emission of Mn2+ ions, with increasing cobalt concentration, confirm the nonradiative energy transfer from Mn2+ to Co2+ ions. On the other hand, temperature dependent measurements show the thermally activated energy transfer process via carriers of the lower energy states for those of the low energy.

Microstructure, composition and magnetic properties of Nd-(Fe1-xCox)-B oxide magnetic particles synthesized by Pechini-type chemical method

This work deals with the investigation and optimization of the crystalline phases, magnetic properties, chemical composition and morphology of Nd-(Fe1-xCox)-B oxide magnetic particles (where x = 0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, and 0.5) synthesized by Pechini method that can be used as a precursor for the production of Nd2(Fe,Co)14B hard magnetic phase. The polymerization mechanism of Pechini process was investigated by Fourier transform infrared (FTIR) and Raman spectroscopy to confirm the formation of metal-CA complexes and successive esterification reactions between citric acid (CA) and ethylene glycol (EG). The chemical composition of the synthesized samples was studied via energy dispersive (EDS) and X-ray photoelectro (XPS) spectroscopy methods. The structure, morphology, and the crystalline phase of resulting Nd-(Fe1-xCox)-B oxide magnetic particles were characterized by Rietveld refinement of X-ray diffraction (XRD) patterns, scanning electron microscopy ( SEM), and high-resolution transmission electron microscopy (HR-TEM) and its selected area electron diffractograms (SAED). The results obtained from the Rietveld refinement of XRD patterns show that (Fe2O3/Fe3O4) phase ratio decreases with the amount of cobalt that can be attributed to the reduction of enthalpy . The SEM micrographs indicate that the oxide particles have an elongated structure with irregular shapes supported by TEM observations. The results of structural analysis by HR-TEM and SAED are consistent with the Rietveld results which confirms the presence of different oxide phases in Nd-(Fe1-xCox)-B oxide particles. The magnetic behaviorstudied by VSM was interpreted by the variances of the morphology, structure and chemical composition of Nd-(Fe1-xCox)-B oxide particles, all of which were influenced by the cobalt content. First‐Order Reversal Curve (FORC) diagrams show that the magnetic interaction between oxide particles decreases as the cobalt content increases.

Microsheets like nickel cobalt phosphate thin films as cathode for hybrid asymmetric solid-state supercapacitor: Influence of nickel and cobalt ratio variation

A rational combination of metal cations is necessary to obtain a synergistic effect leading to improved electrochemical energy storage performance of bimetal compounds. So, the effect of concentration variation of reactants (nickel and cobalt ratio) in nickel cobalt phosphate material and their influence on physicochemical properties and electrochemical capacitive performances are investigated. The morphological evolution from microflowers (nickel phosphate) to microsheets (cobalt phosphate) is observed with increasing cobalt content in nickel cobalt phosphate thin films. The optimum nickel and cobalt composition (∼1:1) in nickel cobalt phosphate (Ni1.38Co1.62(PO4)2·8H2O) thin film electrode demonstrate maximum specific capacitance (capacity) of 1116 F g−1 (446 C g−1) at 0.5 A g−1 current density. Also, a fabricated hybrid asymmetric aqueous device consists of nickel cobalt phosphate thin film as cathode and rGO as an anode in 1 M KOH electrolyte delivers a higher specific capacitance of 120 F g−1 with a high energy density of 42.3 Wh kg−1 at a power density of 1 kW kg−1. Moreover, a hybrid asymmetric solid-state device fabricated using PVA-KOH gel electrolyte exhibits a maximum specific capacitance of 102 F g−1 with an energy density of 36.2 Wh kg−1 at 160 W kg−1 power density and 83.7 % initial capacitance retention after 4000 GCD cycles. Such excellent electrochemical capacitive performance of hybrid asymmetric devices is attributed to the synergy between nickel and cobalt species in nickel cobalt phosphate thin film electrodes, suggesting its potential application as a cathode in hybrid energy storage devices.

Physical Properties of Nanostructured Fe2O3 Thin films - Effect of Cobalt Doping Deposited by CSP

Undoped Fe2O3 and Fe2O3: Co thin films with thickness 350 ± 25 nm deposited by chemical spray pyrolysis CSP method at temperature of 450°C. The results of X-ray measurements analysis revealed a polycrystalline pattern for all samples oriented along (110) plane. The films crystallites were oriented along (110) plane. The Grain size for Undoped showed an increase from 12.47 nm to 14.42 nm upon Cobalt doping, whilst dislocation density (δ) for Undoped showed an decreased from 64.30 to 48.09 upon Cobalt doping, whilst strain (ε) decreased for Undoped showed an decreased from 27.96 to 24.03 upon Cobalt doping. Atomic force microscopy (AFM) tests showed nano particles and a decrease in surface roughness. The root mean square roughness (Rrms) decrease from 6.36 nm to 7.61 nm by increasing the for Undoped Fe2O3 to Fe2O3:2% Co. Transmittance values of undoped Fe2O3 and Cobalt doped films reaches 80% to 90% in Vis- NIR regions. Optical measurements illustrate an increase in the Refractive Index, absorption coefficient and extinction coefficient with increasing Cobalt content in comparison to undoped Fe2O3 thin films.