The bismuth (Bi
)-doped cobalt ferrite nanostructures with dual phase, i.e. cubic spinel with space group Fd3m and perovskite with space group R3c, have been successfully engineered via self-ignited ...sol-gel combustion route. To obtain information about the phase analysis and structural parameters, like lattice constant, Rietveld refinement process is applied. The replacement of divalent Co
by trivalent Bi
cations have been confirmed from energy dispersive analysis of the ferrite samples. The micro-structural evolution of cobalt ferrite powders at room temperature under various Bi
doping levels have been identified from the digital photoimages recorded using scanning electron microscopy. The hyperfine interactions, like isomer shift, quadrupole splitting and magnetic hyperfine fields, and cation distribution are confirmed from the Mossbauer spectra. Saturation magnetization is increased with Bi
-addition up to x = 0.15 and then is decreased when x = 0.2. The coercivity is increased from 1457 to 2277 G with increasing Bi
-doping level. The saturation magnetization, coercivity and remanent ratio for x = 0.15 sample is found to be the highest, indicating the potential of Bi
-doping in enhancing the magnetic properties of cobalt ferrite.
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Porous microspheres copper cobalt carbonate hydroxides (CuxCo2⿿xCH) pseudocapacitive electrode material comprised of nanoplates via a facile hydrothermal method were presented. ...Significantly, the crystalline structure, morphology and electrochemical performance of the CuxCo2⿿xCH can be readily manipulated by varying the Cu/Co molar ratios. Among various stoichiometries of CuxCo2⿿xCH porous microspheres studied, Cu1.79Co0.21CH consisted of nanoplates with a mean thickness of ⿼35nm showed a high specific capacitance of 789Fg⿿1 at a current destiny of 1Ag⿿1 and good rate ability. Furthermore, the optimized Cu1.79Co0.21CH electrode also exhibited remarkable high cycling stability, ca 77.5% after 3000 charge/discharge cycles at current density of 5Ag⿿1. An asymmetric device was constructed from optimized Cu1.79Co0.21CH materials on nickel foam (NF) as cathode electrode and graphene on NF as anode electrode in a 6M KOH electrolyte. The asymmetric Cu1.79Co0.21CH/NF//graphene/NF supercapacitor device delivered a specific capacitance of 60.5Fg⿿1 in a potential range of 0⿿1.6V. A high energy density of 21.5Whkg⿿1 was achieved at the power density of 200Wkg⿿1. More significantly, the designed device exhibited excellent cycling stability with 73.3% capacity retention after 5000 cycles.
The drastic volume expansion and dendrite growth of lithium metal anodes give rise to poor electrochemical reversibility. Herein, ZnO, N dually doped nanocages (c-ZNCC) were synthesized as the host ...for lithium metal anodes using the zeolitic imidazolate framework-8 (ZIF-8). The synthesis is based on a two-step core@shell evolution mechanism, which could guide lithium deposition rapidly and offer a fast lithium-ion diffusion during the cycling process. Benefiting from the unique design, the as-obtained c-ZNCC can render a record short lithium infusion as low as 1.5 s, a stable lithium stripping/plating capability as long as 3000 h, and a voltage hysteresis of 95 mV when cycling at 10 mA cm–2 to 10 mA h cm–2. A low Tafel slope of 3.45 mA cm–2 demonstrates the efficient charge transfer of c-ZNCC-Li, and the galvanostatic intermittent titration technique measurement shows high diffusion coefficient of c-ZNCC-Li during the charging process. In addition, the LNMO||c-ZNCC-Li cell exhibits a capacity retention as high as 93.7% at 1 C after 200 cycles. This work creates a new design for deriving nanocages with dual lithiophilic spots using a metal–organic framework and carbon cloth for favorable Li metal anodes.
•Synthesis of single spinel phase Co-Zn-La nano ferrites.•Magnetization controlled by La composition, crystal size and YK angle of spin canting.•Electron hopping is responsible for the dielectric ...polarization.•The ε′ increases and tanδ decreases with the increasing La composition.
Co-Zn spinel ferrites with lanthanum (La3+) ion substitutions having formula Co0.7Zn0.3LaxFe2-xO4 (x = 0.0, 0.025, 0.05, 0.075, 0.1) were prepared using sol gel auto ignition route. The structural characterization of the ferrites was performed by the x-ray diffraction (XRD) method. The parameters calculated from the XRD analysis include lattice parameter, density, porosity, crystal size and lattice strain. The nanocrystallinity of the ferrite samples was observed with the crystallites of 20–30 nm size. The scanning electron microscopy (SEM) was employed to analyse the morphology of the ferrite crystals. The size and shape of the ferrite nanocrystals were confirmed from transmission electron microscopy (TEM) images. The crystal planes revealed from XRD calculations were confirmed by the selected area electron diffraction (SAED) analysis of the ferrites. Vibrating sample magnetometer (VSM) measurements of the ferrite samples were performed to study the magnetic properties of the ferrites. The effects of the La3+ substitution were observed on the coercivity and saturation magnetization of the ferrites. The variation of dielectric properties of the ferrites within 50 Hz to 5 MHz frequency band were studied at room temperature. The dielectric relaxation in the ferrites was governed by the electron hopping between divalent (Fe2+ and Co2+) and trivalent (Fe3+ and Co3+) cations. Remarkable impact of La3+ composition and the crystal size was observed on dielectric constant as well as loss tangent.
The Ni-rich layered oxide cathode has shown high energy density, proper rate capability, and longevity of the rechargeable battery, while poor stability and capacity fading are assumed to be its ...common cons. To address this obstacle, prospective cathode materials are synthesized by integrating the lithium transition metal oxides with an artificial cathode electrolyte interphase (CEI) layer. Herein, plasma-enhanced atomic layer deposition (PEALD) is employed to coat the LiNi0.8Mn0.1Co0.1O2 (NMC811) electrode with Al2O3 and MoO3. The combined results from morphological examinations revealed the formation of uniform Al2O3 and MoO3 sheets after 200 cycles of PEALD coating. Consistent results from the XRD analysis demonstrate that Al2O3 and MoO3 artificial CEIs can reduce Li–Ni mixing. The cyclic voltammetry tests show the oxidation–reduction kinetic. The modified NMC811 structures with Al2O3 and MoO3 represent a remarkable improvement in terms of capacity retention. The coated cathode with Al2O3 clearly outperforms the modified configuration with MoO3 concerning ionic conductivity, charge/discharge reversibility, and capacity retention. The promising results obtained in this study open the possibility of synthesizing Ni-rich cathodes with enhanced electrochemical performance.
Exploring combinatorial materials, as well as rational device configuration design, are assumed to be the key strategies for deploying versatile electrochemical devices. MXene sheets have revealed a ...high hydrophilic surface with proper mechanical and electrical characteristics, rendering them supreme additive candidates to integrate in electrospun electrochemical power tools. The synergetic effects of MXene 2D layers with the nanofibrous networks can boost actuator responsive ability, battery capacity retention, fuel cell stability, sensor sensitivity, and supercapacitor areal capacitance. Their superior mechanical features can be endowed to the electrospun layers through the embedding of the MXene additive. In this review, the preparation and inherent features of the MXene configurations are briefly evaluated. The fabrication and overall performance of the MXene‐loaded nanofibers applicable in electrochemical actuators, batteries, fuel cells, sensors, and supercapacitors are comprehensively figured out. Eventually, an outlook on the future development of MXene‐based electrospun composites is presented. A substantial focus has been devoted to date to engineering conjugated MXene and electrospun fibrous frames. The potential performance of the MXene‐decorated nanofibers presents a bright future of nanoengineering toward technological growth. Meanwhile, a balance between the pros and cons of the synthesized MXene composite layers is worthwhile to consider in the future.
Combinatorial materials in form of electrospun nanofibers exhibit enormous potential toward advancing the performance of electrochemical devices. This review briefly presents the synthesis of MXene based composite nanofibers by electrospinning technique and their potential applications in energy technologies. MXene based engineering of nanofibers via electrospinning and corresponding properties are the main focus in milieu of sensing and energy technologies.
Novel spruce leaf-like copper bismuth oxide (CuBi2O4) microstructured films have been deposited on stainless steel (SS) substrate by using a simple and cost-effective electrodeposition chemical ...route. The morphology of CuBi2O4 was studied using field emission scanning electron microscopy (FESEM) whereas X-ray diffraction (XRD) spectra recorded for phase confirmation. The spruce leaf-like architecture composed of nanoparticles was evidenced for the obtained CuBi2O4 material. The supercapacitor performance for prepared CuBi2O4 electrode calcined at 200, 300, 400, 500 °C temperatures were investigated. The cyclic-voltammetry and charge-discharge studies were carried out at different scan rates and current densities respectively. The highest specific capacitance 484 F/g was noted for CuBi2O4 electrode calcined at 500 °C at 10 mV/ s scan rate via cyclic-voltammetry analysis in 1 M NaOH electrolyte. The specific capacitance of 540.9 F/g was estimated from charge-discharge analysis at 10 mA/cm2 current density. The energy density of 146.8 Wh/Kg and power density 1555.5 W/Kg for optimized CuBi2O4 electrode at 10 mA/cm2 current density. The electrochemical impedance spectroscopy studies were also performed. The nanostructured CuBi2O4 material has exhibited supercapacitive properties for energy storage applications.
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•Novel spruce leafs-like CuBi2O4 microstructures synthesis by electrodeposition.•CV, charging discharging studies of different calcined CuBi2O4 electrodes.•EIS measurements of CuBi2O4 electrode was measured.•High specific capacitances, energy and power densities of CuBi2O4 electrode.
The current collector serves as a crucial element in supercapacitors, acting as a medium between the electrode material and the substrate. Due to its excellent conductivity, a metal collector is ...typically favored. Enhancing the binding strength between the collector and the substrate as well as between the collector and the electrode material has emerged as a critical factor for enhancing the capacitance performance. In this study, a Ag film with a grass root-like structure was initially grown on a PI substrate through the surface modification and ion exchange (SMIE) process. This Ag interlocking structure contributes to strong binding between the PI substrate and Ag without compromising the mechanical properties of the Ag film. To further enhance the electrochemical properties at low scan rates, electroless-plated Cu was subsequently deposited on the Ag film to form the Cu/Ag current collector. Moreover, the Cu within the Cu/Ag current collector served as a precursor for the growth of FeOOH-Cu(OH)2 via a two-step in situ method. The resulting FeOOH-Cu(OH)2/Cu/Ag structure as a whole is binder-free. Supercapacitors employing symmetric FeOOH-Cu(OH)2/Cu/Ag structures were assembled, and their energy storage properties were investigated. The solution-based low-temperature process used in this study offers the potential for cost-effective and large-scale applications.
Detecting smoke at room-temperature using unrealistic metal oxide-based sensor is the most important component in a fire alarm system. We report on highly sensitive and selective chemically grown ...porous hydrangea-type bismuth molybdate (Bi2MoO6) room-temperature smoke and humidity sensor. The as-synthesized Bi2MoO6 sensor has been initially screened for its structure, morphology, surface elemental composition, type of conductivity and porosity measurements by various means and then is exposed to different gases like ammonia, acetone, ethanol, methanol, and benzaldehyde as a room-temperature i.e., 25 ºC. Hydrangea-type nanocrystalline and mesoporous n-type Bi2MoO6 sensor demonstrates a sensitive response of 59% towards 40 vol% smoke with a fast response/recovery time of 60/14 s at room-temperature which would find a potential use in a fire alarm system. Despite of n-type semiconducting nature, Bi2MoO6 sensor endows quite good response after the exposure of smoke. Effect of smoke concentration and relative humidity on sensor resistance followed performance has also been explored. The alterations in band bending, under various operation conditions, are illustrated using schematic structural views with the help of possible structural images.
•Metal oxide nanocomposite.•Eco-friendly, cost effective chemical bath deposition synthesis.•Smoke sensor with high detection ability.•Volatile organic compound.
Lithium-ion batteries (LIBs) are accounted as promising power tools, applicable in a wide range of energy-based equipment, from portable devices to electric vehicles. Meanwhile, approaching a ...cost-effective, environmentally friendly, and safe LIB array has remained sluggish yet. In this regard, cellulose, as a nontoxic natural renewable polymer, has provided a stable and cohesive electrode structure with excellent mechanical stability and reduced electrode cracking or delamination during cycling. Additionally, the porous configuration of the cellulose allows for efficient and faster ion transport as a separator component. Miniaturizing cellulose and its derivatives have revealed more fabulous characteristics for the anode, cathode, and separator resulting from the increased surface-to-volume ratio and superior porosity, as well as their thin and lightweight architectures. The focal point of this review outlines the challenges relating to the extraction and electrospinning of cellulose-based nanofibers. Additionally, the efforts to employ these membranes as the LIBs' components are elucidated. Correspondingly, despite the great performance of cellulose-based LIB structures, a research gap is sensed in this era, possibly due to the difficulties in processing the electrospun cellulose fibers. Hence, this review can provide a source of recent advancements and innovations in cellulose-based electrospun LIBs for researchers who aim to develop versatile battery structures using green materials, worthwhile, and eco-friendly processing techniques.
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