Cobalt Zinc Research Articles

α‐Ga2O3‐Based Heterojunction Diodes and Junction Field‐Effect Transistors

This article presents a comprehensive investigation into the suitability of diverse p‐type materials for the fabrication of pn‐heterojunctions and junction field‐effect transistors (JFETs) with α‐Ga2O3. The electrical properties of these materials are examined in detail and compared with one another in order to ascertain their relative merits. Therefore copper iodide (CuI), zinc cobalt oxide (ZCO), and nickel oxide (NiO) are used as p‐type contacts. The smallest ideality factors are obtained for pn‐heterojunctions utilizing CuI, whereas the highest current rectification is obtained for diodes with NiO and ZCO contacts, if an oxygen plasma treatment of the α‐Ga2O3 is performed before the deposition of the p‐type electrode. This way current rectification ratios of up to are achieved. In a next step, these findings are used to fabricate highly functional JFETs with a α‐Ga2O3 channel. These devices exhibit current on/off ratios of up to and small mean sub‐threshold swings of at a low drain voltage of 3 V. High breakdown voltages of up to 418 V are achieved, regardless of the gate material.

Synthesis and application of zinc cobalt oxide/sulfide nanorods for photocatalytic water splitting and carbon dioxide reduction

Synthesis and application of zinc cobalt oxide/sulfide nanorods for photocatalytic water splitting and carbon dioxide reduction

Facile Synthesis of Zinc Cobalt Sulfide and Composite with Graphitic Carbon Nitride (ZCS@GCN) for Photocatalysis and Electrode for Energy Storage Applications

Facile Synthesis of Zinc Cobalt Sulfide and Composite with Graphitic Carbon Nitride (ZCS@GCN) for Photocatalysis and Electrode for Energy Storage Applications

Enhanced Electrochemical Detection of Orthophosphate in Potable Water Using Zinc-Cobalt Oxide Nanocomposite-Modified Nickel Foam Electrodes

Abstract This study presents a novel approach to electrochemical detection of orthophosphate in potable water using hydrothermally synthesized nickel foam electrodes, modified with cobalt oxide (CoOx), zinc oxide (ZnOx), and zinc-cobalt oxide (ZnCoOx) nanocomposites. The incorporation of zinc-cobalt oxide into the electrode significantly enhances its stability and detection capability. In-situ phosphate detection was performed using voltammetric techniques in a highly alkaline environment (pH 14) facilitated by sodium hydroxide (NaOH). Comprehensive electrode characterization, including cyclic voltammetry (0 to 0.6 V at a scan rate of 50 mV/s), electrochemical impedance spectroscopy (105 to 10-2 Hz), scanning electron microscopy, and energy-dispersive X-ray spectroscopy, confirmed the superior performance of the synthesized electrodes. Among the tested configurations, the zinc-cobalt oxide nanocomposite on nickel foam exhibited outstanding sensitivity, with a sensitivity of 0.4 μA/μM across a concentration range of 0 to 40 μM, and an elevated sensitivity of 4.26 μA/μM within the 50 to 100 μM range. The electrode achieved a remarkably low detection limit of 0.171 μM/L (0 to 40 μM detection range) and 0.324 μM/L (50 to 100 μM, detection range), underscoring its potential for highly accurate phosphate detection. These findings highlight the sensor's applicability for diverse practical uses in water quality monitoring.

Electrospun PAN@Ferrites Nanofibers for Rectifier and Humidity Devices

Zinc cobalt ferrite (ZnCoFe2O4) and zinc ferrite (ZnFe2O4) were prepared using the sol-gel synthesis. composite materials, PAN@CoFe2O4 and PAN@ZnCoFe2O4, were created by combining polyacrylonitrile (PAN) polymer with ZnCoFe2O4 and ZnFe2O4. Electrospinning was used to apply thin coatings onto glass and p-Si wafers. The synthesized fibre for both pure PAN polymers and their ferrite-based composites was illustrated in Field Emission Scanning Electron Microscopy (FESEM) images. The X-ray diffraction (XRD) analysis reveals that the PAN polymer exhibits a prominent peak at a precise angle of 29. 3345°.The size of this peak remains constant in PAN composites containing ZnCoFe2O4 and CoFe2O4. Fourier transformer infrared (FTIR) shows that absorptions have stretching vibrations between metal and oxygen. Nanofiber composites display non-ohmic characteristics, as evidenced by current-voltage (I-V) tests. PAN nanofibers display conductive properties, whilst their ferrite composites demonstrate rectification behaviour at room temperature when subjected to a low applied field. For PAN NFs, there is no effect when relative humidity percentage increases and decreases, but with adding ferrite materials PAN@ZnFe2O4 and PAN@ZnCoFe2O4 where, there is a significant change in resistance when humidity increases and decreases.

Variations in the optical and thermoelectric behavior of ZnCo2O4 nanostructures as a function of synthesis temperature

Zinc cobalt oxide nanostructures were synthesized by electrochemical deposition of zinccobalt alloy at various bath temperatures (15, 30, 45 and 60 ˚C) and its hydrothermal oxidation at 100 ˚C. X-ray diffraction pattern and Raman spectroscopy data reveals the formation of spinal structure of ZnCo2O4. Photoluminescence spectra of the samples exhibit broad peaks with a red shift in the emission energy. Diffused reflectance spectroscopy measured the band gap of the synthesized materials; band gap is 3.06, 3.03, 3.02 and 2.99 eV, for samples electrodeposited at 15, 30, 45 and 60 ˚C, respectively. Optical conductivity of synthesized materials decreases with increasing deposition layers while reflectance shows opposite trend. Thermoelectric set up measures the change in potential difference through synthesized materials when different temperatures are applied and an increment in potential were observed. Seebeck co-efficient and power factor are also studied as function of bath temperature.

Zinc cobalt sulfide with carbon (graphene oxide and CNT) based nanocomposite as positive electrode for asymmetric coin cell supercapacitors

Abstract The world dependence on portable electronic devices has increased the demand for high-performance energy storage devices. The use of transition metal sulfides as faradaic electrode materials for electrochemical energy storage is rapidly increasing due to their high energy density. Herein Zinc Cobalt Sulfide (ZCS) with graphene oxide (GO) and carbon nanotubes (CNT) were used to create an interconnected ZCS composite network using a solvothermal technique. The materials were characterized by utilizing XRD, FT-Raman, TGA, FESEM/EDX, XPS, and BET. The electrochemical performance of the materials was examined using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The prepared electrodes exhibited both pseudocapacitor behavior and double-layer capacitor behavior, indicating the hybrid nature. Furthermore, All the electrode ZCS, ZCS/GO, ZCS/CNT, and ZCS/GO/CNT electrodes demonstrated higher capacitance behavior, with values of 420, 551, 585 and 811 F g−1 at 1 A/g. Among these ZCS/GO/CNT electrode exhibits outstanding electrochemical properties, with a notable retention of 81.08% at 10 Ag−1 because Combining ZCS nanoparticles with interconnected GO and CNT provides excellent electronic conductivity and stability. The assembled ZCS/GO/CNT//graphene oxide asymmetric coin cell (ACC) supercapacitor showed a high energy density of 33.3 Wh kg–1 at a power density of 624 W kg–1. The 3D nanostructure of ZCS/GO/CNT/Graphene oxide has great potential for developing foldable energy storage devices.

Investigation of electrical, dielectric, magnetic and electrochemical characteristics of a BaFe12O19/Co0.5Zn0.5Fe2O4 nanocomposite

BaFe12O19 (barium ferrite, i.e., BaF) nanoparticles, Co0.5Zn0.5Fe2O4 (cobalt zinc ferrite, i.e, CZF) nanoparticles and their nanocomposite were synthesized for the investigation of electrical, magnetic, dielectric, and electrochemical properties. The X-ray diffraction (XRD) pattern revealed the formation of hexagonal structure for BaF nanoparticles and cubic structure for CZF nanoparticles with crystallite size of 32.44 nm and 31.30 nm, respectively. Whereas, for nanocomposite, the crystallite size obtained is 34.21 nm were shifting of peaks revealed the formation of nanocomposite. The Fourier transform Infrared (FTIR) spectra revealed the presence of metal-oxygen vibrational peaks for all the samples. The dielectric data revealed the increase in dielectric constant of nanocomposite as compared to pristine CZF whereas, loss reduced for nanocomposite significantly. Single semicircle in Nyquist plot for all the samples revealed the contribution of grain resistance in impedance. The hysteresis loop showed the increase in specific saturation magnetization from 16.963 emu/g to 21.305 emu/g for nanocomposite when compared with pristine BaF. Whereas specific remnant magnetization increased to 10.305 emu/g for nanocomposites. The electrochemical properties presented by Cyclic voltammetry showed the presence of cathodic and anodic peaks which revealed the presence of redox reaction in all samples. The specific capacitance calculated for all samples at different scan rate revealed that a nanocomposite showed highest Cs value 16.43 F/g at 25 mV, whereas it increased to 27.01 F/g, 35.93 F/g and 38.87 F/g with the increase in scan rate to 50 mV, 75 mV and 100 mV, respectively.

Temperature-dependent dielectric measurements of polypyrrole/zinc cobalt oxide nanocomposites by impedance spectroscopy

This study characterizes the conduction mechanism in Zinc Cobalt oxide/Polypyrrole nanocomposites (ZCO/PPy NCs) concerning temperature (303–453 K) and frequency (100 Hz–1 MHz). To obtain the ZCO/PPy nanocomposites for the experiments, we used the in-situ chemical polymerization technique to disseminate varying weight percentages of ZCO nanoparticles (ZCO NPs) in the PPy matrix. The total electrical conductivity graph consists of a step-like feature of a plateau and dispersive regimes. The dispersive zone, which follows Jonscher's power law, correlates to AC conductivity, whereas the plateau region, which corresponds to DC conductivity, is thermally activated. The extracted DC conductivity values are of the order of 10‐4 S/m at 303 K. The conduction mechanism in ZCO/PPy nanocomposites is depicted by the Non-Overlapping Large Polaron Tunneling (NSPT) model. The dielectric studies confirm the non-Debye-like relaxation in PPy and ZCO/PPy NCs. In addition, the complex impedance and equivalent circuit analysis showed maximum contribution from grain and grain boundaries. The grain and grain boundary resistances are of the order of 103 Ω, depicting the electrical homogeneity in the PPy and ZCO/PPy nanocomposites.

Electrodeposited zinc cobalt bimetallic phosphate as a bifunctional catalyst for hydrogen evolution and urea oxidation

The theoretical potential of the urea oxidation reaction (UOR) is a mere 0.37 V(vs.RHE), significantly lower than the 1.23 V (vs. RHE) of the oxygen evolution reaction (OER). Thus, substituting the OER with the UOR can effectively reduce the voltage required for electrolysis. Transition metal phosphates (TM-Pi), with their unique physical properties, can partly replace precious metal catalysts and hold great application potential. However, further modification is necessary to enhance their catalytic activity and stability. Therefore, this study prepared a coral-like cluster Co/Zn-Pi@NF (Pi represents phosphate) catalyst, which was grown in situ on nickel foam (NF) using the constant current electrodeposition method. The catalyst exhibited superior catalytic performance in 1 M KOH, with the required overpotentials for the hydrogen evolution reaction (HER) and OER reaching 10 mA·cm−2 being 36.6 mV and 343.4 mV, respectively. In 1 M KOH containing 0.5 M urea, the urea oxidation potential was only 1.4 V, which remained stable for 60 hours. The Co/Zn-Pi@NF nanoparticles were used as the anode and cathode for water-urea electrolysis, and the electrolysis voltage was 1.43 V at a current density of 10 mA·cm−2, which was 290 mV lower than that of electrolyzed water. This study demonstrates that zinc-cobalt bimetallic phosphate can be used as a dual-function electrocatalyst for hydrogen evolution and urea oxidation.

Ultra-sensitive zinc cobaltate assembled on N-rich carbon nitride electrochemical sensor for the detection of paraquat in food samples

BackgroundParaquat (PQ) from agricultural waste cause contamination in water bodies, groundwater, soil, and foods has received increasing attention regarding health safety. On-site-based detection is much needed along with rapid results, selectivity and sensitivity, which can be achieved through an electrochemical-based sensor. MethodsThis work provides, an electrochemical sensor based on zinc cobaltite (ZnCo2O4) nanostructure strongly attracted through electrostatic interaction with the carbon nitride (C3N5; CN) nanosheets modified on a glassy carbon electrode (GCE) for the determination of paraquat (PQ). The strong immobilization of ZnCo2O4 over CN2 on GCE synergistically shows excellent sensing of PQ due to high interfacial charge transfer effect. Significant findingsIn addition, the electrochemical studies were performed using CV and DPV analysis which exhibits a good limit of detection (7.6 nM) and sensitivity (0.201 µA cm-2) towards PQ detection. Furthermore, the modified electrode was applied practically in real food samples for PQ detection with excellent recoveries.

Improving the Mechanical and Radiation Shielding Parameters of Sodium Cobalt Zinc Borate Glass for Radiation Shielding Purposes

Improving the Mechanical and Radiation Shielding Parameters of Sodium Cobalt Zinc Borate Glass for Radiation Shielding Purposes

Copper-doped zinc cobalt sulfide nanosheets as advanced bifunctional electrocatalysts for sustainable hydrogen production via electrochemical water splitting

Copper-doped zinc cobalt sulfide nanosheets as advanced bifunctional electrocatalysts for sustainable hydrogen production via electrochemical water splitting

Tailoring magnetism in chromium-doped zinc cobalt ferrite nanostructure for advanced spintronic memory devices

Soft magnetic ferrites serve as a crucial component in a wide array of sensing and actuating applications across various industries, including consumer electronics, automotive systems, spintronics, and more. These materials also find utility in spintronics, particularly for next-generation magnetic random-access memory (MRAM) due to their excellent inductive properties, which enhance the performance and scalability of spintronic memory devices. This study focuses on fine-tuning soft magnetic ferrites for inductive applications by doping them with Cr ions. By utilizing advanced experimental techniques such as the vibrating sample magnetometer (VSM) for bulk magnetometry and X-ray magnetic circular dichroism (XMCD) alongside X-ray absorption spectroscopy for atomic studies, the research aims to investigate the structural, electronic, and magnetic properties of the nanoferrites. Addition of doping in the soft ferrites observes reduction in the general magnetic parameters, with the only exception being coercivity, which decreases from 381 Oe to 275 Oe as the doping concentration increases from x = 0 to x = 0.02, and then increases to 350 Oe at x = 0.03. Through such precise tuning of the nanoparticles, this study aims to investigate the controllable soft magnetic properties of the nanoferrites, thereby paving the way for fast access times, non-volatility, and low energy consumption, presenting a compelling alternative to conventional memory technologies.

Synthesis and characterization of zinc cobalt sulphide nanofilms for optoelectronic applications

Zinc-cobalt sulphide (ZnxCo1−xS) thin films were fabricated on glass substrates using the chemical bath deposition (CBD) technique. In this study, the films were grown employing solutions of zinc acetate, cobalt sulphate, and thioacetamide as the respective sources of zinc, cobalt, and sulphur. The synthesized films were investigated for their potential use in optoelectronic device applications. Optical characterization revealed that the films exhibited a direct transition with an energy gap ranging from 3.350 to 3.360 ​eV. As the zinc concentrations were changing, the absorbance of the films were decreasing uniformly along the wavelength spectra. The films exhibit a low extinction coefficient (0.0–0.23) that may be due to the internal reflections within the material as concentrations changes. Variations in the thickness, reflectance and refractive index with zinc concentrations were also discussed. The electrical resistivity was found to decrease from 7.12×108 to 5.94×108 (Ω.cm) with zinc concentrations. According to the crystallography spectrum, ZnxCo1−xS has a polycrystalline structure with various distinct peaks at different orientations. Scanning electron microscopy shows that surface morphology of ZnxCo1−xS films has a well-defined nanoparticles of different shapes and sizes which are uniformly distributed and are significantly transformed as a function of concentrations. The results demonstrate that the chemically deposited thin films can be engineered for a range of optoelectronic applications.

Construction of cobalt zinc metal-organic frameworks derived Co/CoO/C composites toward broadband and high-efficiency electromagnetic wave absorption

The fabrication of novel carbon-based electromagnetic wave (EMW) absorbers with broad absorption bandwidth, strong absorption strength, low filler loading ratio and thin matching thickness remains a challenging task. Metal-organic frameworks (MOFs) are widely recognized as ideal self-sacrificial templates for the construction of carbon-based EMW absorbers. In this work, bimetallic CoZn-MOFs derived Co/CoO/C composites were prepared by combining magnetic stirring with subsequent pyrolysis treatment. The results showed that the morphology of carbon skeletons evolved from an irregular agglomerate to a uniform hexagonal star shape and then to an agglomerate again by reducing the molar ratio of Co2+ to Zn2+. Remarkably, excellent EMW absorption capacity in the Ku-band was achieved through carefully regulating the molar ratio of Co2+ to Zn2+. When the filling ratio was 20 wt%, the prepared Co/CoO/C composite exhibited the best EMW absorption performance with the minimum reflection loss of −64 dB at a thickness of 1.79 mm and the maximum effective absorption bandwidth of 6 GHz at a thickness of 2.14 mm. Furthermore, the radar cross section in the far-field was simulated by computer simulation technique. In addition, the possible EMW attenuation mechanism was proposed. Therefore, the results of this paper could be helpful for developing carbon-based magnetic composites derived from MOFs as broadband and high-efficiency EMW absorbers.

Fabrication of ZnCo2O4-Zn(OH)2 Microspheres on Carbon Cloth for Photocatalytic Decomposition of Tetracycline.

Zinc cobalt oxide-zinc hydroxide (ZnCo2O4-Zn(OH)2) microspheres were successfully fabricated on carbon cloth via a sample hydrothermal method. The surface morphology of these microspheres and their efficacy in degrading methyl violet were further modulated by varying the thermal annealing temperatures. Adjusting the thermal annealing temperatures was crucial for controlling the porosity of the ZnCo₂O₄-Zn(OH)₂ microspheres, enhancing their photocatalytic performance. Various analytical techniques were utilized to evaluate the physical and chemical properties of the ZnCo2O4-Zn(OH)2 microspheres, including field-emission scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, field-emission transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. Compared to untreated ZnCo2O4-Zn(OH)2 microspheres, those subjected to thermal annealing exhibited increased specific surface area and light absorption capacity, rendering them highly effective photocatalysts under UVC light exposure. Subsequent studies have confirmed the superior performance of ZnCo2O4-Zn(OH)2 microspheres as a reusable photocatalyst for degrading methyl violet and tetracycline. Furthermore, trapping experiments during the photodegradation process using ZnCo₂O₄-Zn(OH)₂ microspheres identified hydroxyl radicals (·OH) and superoxide radicals (·O₂⁻) as the primary reactive species.

Optical analysis of ferrite films using spectroscopic ellipsometry

This work presents the optical properties of nickel zinc ferrite, nickel copper zinc ferrite, and nickel cobalt zinc ferrite films prepared on Si/SiO2 substrates using the sol-gel and spin-coating technique. A J.A. Woollam Company RC2 model D variable angle spectroscopic ellipsometer was used to measure the amplitude ratio (Ψ) and phase difference (Δ) of the films annealed at two distinct temperatures (500 and 800 °C). Measurements were taken at three incident angles (55°, 65°, and 75°) across the spectral range of 190–1000 nm, with a step size of 1 nm. The acquired data were subjected to modeling using a summation of Kramers–Kronig consistent oscillators to determine the film thickness and complex optical functions (refractive index and extinction coefficient) with a minimized mean-squared error. Additionally, incorporating a surface roughness layer notably enhanced the accuracy, with the roughness described using the Bruggeman effective medium approximation reflecting a 50%–50% mixture between the film's optical constants and those of air (void). The experimental and simulated (Ψ, Δ) spectra as a function of wavelength at angles 55°, 65°, and 75° for the NZF, NCuZF, and NCoZF films annealed at 500 and 800 °C are provided. The refractive index and extinction coefficient values as a function of wavelength for NZF, NCuZF, and NCoZF films annealed at 500 and 800 °C are also included. The elucidated optical properties of these films hold potential for application in various optoelectronic devices, including solar cells.

Zero-Background Dual-Mode Closed Bipolar Electrode Electrochemiluminescence Biosensor Based on ZnCoN-C Potential Regulation for Ultrasensitive Detection of Ochratoxin A.

In this work, the relationship between electrochemiluminescence (ECL) signal and driving voltage was first studied by self-made reduced and oxidized closed bipolar electrodes (CBPEs). It was found that when the driving voltage was large enough, the maximum ECL signals for the two kinds of CBPEs were the same but their required drive voltages were different. Zinc cobalt nitrogen doped carbon material (ZnCoN-C) had an outstanding electric double layer (EDL) property and conductivity. Therefore, it could significantly reduce the driving voltage of two kinds of CBPE systems, reaching the maximum ECL signal of Ru(bpy)32+. Interestingly, when the ZnCoN-C modified electrode reached the maximum ECL signal, the bare electrode signal was zero. As a proof-of-concept application, a zero-background dual-mode CBPE-ECL biosensor was constructed for the ultrasensitive detection of ochratoxin A (OTA) in beer. Considering that beer samples contained a large number of reducing substances, a reduced CBPE system was selected to build the biosensor. Furthermore, a convenient ECL imaging platform using a smartphone was built for the detection of OTA. This work used a unique EDL material ZnCoN-C to regulate the driving voltage of CBPE for the first time; thus, a novel zero-background ECL sensor was constructed. Further, this work provided a deeper understanding of the CBPE-ECL system and opened a new door for zero-background detection.

Fabrication of a reusable carbon quantum dots (CQDs) modified nanocomposite with enhanced visible light photocatalytic activity

In awareness of industrial dye wastewater, carbon quantum dots (CQDs) and cobalt zinc ferrite (CZF) nanocomposites were synthesised for the making of carbon quantum dots coated cobalt zinc ferrite (CZF@CQDs) nanophotocatalyst using oxidative polymerization reaction. The results of TEM, zeta potential value, and FTIR confirm highly dispersed 1–4 nm particles with the − 45.7 mV carboxylic functionalized surface of CQDs. The results of the synthesised CZF@CQDs photocatalyst showed an average particle size of ~ 15 nm according to TEM, SEM, and XRD. The photocatalyst showed a 1.20 eV band gap, which followed the perfect visible light irradiation. TGA and DTA revealed the good thermal stability of the nanophotocatalyst. VSM was carried out, and the saturation magnetisations for CZF and CZF@CQDs were 42.44 and 36.14 emu/g, respectively. A multipoint study determined the BET-specific surface area of the CZF@CQDs photocatalyst to be 149.87 m2/g. Under visible light irradiation, the final CZF@CQDs nanophotocatalyst demonstrated remarkable efficiency (~ 95% within 25 min) in the photocatalytic destruction of Reactive Blue 222 (RB 222) and Reactive Yellow 145 (RY 145) dyes, as well as mechanical stability and recyclability. Even after the recycling of the degradation study, the nanophotocatalyst efficiency (~ 82%, 7th cycles) was predominantly maintained. The effects of several parameters were also investigated, including initial dye concentration, nanophotocatalyst concentration, CQD content, initial pH of the dye solution, and reaction kinetics. Degradation study data follow the first-order reaction rate (R2 > 0.93). Finally, a simple and low-cost synthesis approach, rapid degradation, and outstanding stability of the CQD-coated CZF nanophotocatalyst should make it a potential photocatalyst for dye wastewater treatment.