Binary Metal Oxides Research Articles

Binary transition metal oxide: A novel and efficient catalyst for the synthesis of boron nitride nanotubes

AbstractA novel binary transition metal oxide (NiFe2O4) nanosphere catalyst with a diameter of 500 nm has been synthesized by the hydrothermal reaction, which can efficiently catalyze the formation of hexagonal boron nitride nanotubes (BNNTs) with high‐yield and large aspect ratio. Based on the temperature dependence of the product phase composition and microstructure, combined with results generated using single‐component catalysts, the BNNTs formation process can be summarized as follows: NiFe2O4 reacts with NH3 to generate Fe0.64Ni0.36, which dissolves to form a liquid‐phase Ni‐Fe alloy at high temperatures, where the B component in the precursor and the N atom formed by the decomposition of NH3 diffuse on the surface of the Ni‐Fe alloy; when the concentration of B and N exceed the saturation threshold, hollow BNNTs containing catalyst at the tips are precipitated. The formation process is dominated by a vapor‐liquid‐solid mechanism with tip‐growth mode, where the synergistic catalytic effect of the Ni‐Fe binary system promotes a high yield of large aspect ratio BNNTs.

Room temperature and rapid synthesis of ZnMn2O4 nanostructured spinel using deep eutectic solvent for high energy asymmetric supercapacitors

Recently, binary metal oxides have drawn significant attention due to their interesting physico-chemical characteristics, makes them suitable for supercapacitor application. In the present work, high surface area spinel ZnMn2O4 is prepared using a reaction of deep eutectic solvent (DES) containing zinc chloride, choline chloride and glycerol with manganese precursor (KMnO4). The DES serves as both precursor and template for the growth of ZnMn2O4. Interestingly, the spinel structure of ZnMn2O4 is prepared within one-minute time at room temperature using DES route makes this process cost-effective. The reaction between DES and manganese precursors can be halted at any stage with the addition of water to the reaction mixture as it reduces existing bonding interaction between the reactants. With this advantage, we have varied reaction time between DES and KMnO4 and further studied the effect of reaction time on surface area and electrochemical properties of the obtained ZnMn2O4. The ZnMn2O4 sample, where DES and KMnO4 reacted for 10 min (ZnMnO-10) showed highest surface area of 118.5 m2/g with a pore volume of 0.19 cm3/g. Further, the ZnMnO-10 sample showed a good specific capacitance of 499.58 F/g at 0.1 A/g in a neutral electrolyte (1 M Na2SO4). The symmetric supercapacitor device fabricated using ZnMnO-10//ZnMnO-10 with energy and power density of 39.40 Wh/kg and 7.06 kW/kg, respectively. Further, the asymmetric supercapacitor device is also assembled using ZnMn2O4 and agro waste-derived carbon (HBC-800) showed an excellent Csp of 331.24 F/g at 0.2 A/g with energy density and power density of 74.50 Wh/kg and 5.4 kW/kg, respectively. The current work proposes the rapid and facile synthesis of spinel ZnMn2O4 utilizing green DES and the obtained ZnMn2O4 showed good specific capacitance and energy density for both symmetric and asymmetric supercapacitor devices.

Fabrication of NiO-CuO/RGO Composite for Lithium Storage Property

The lithium storage performance of binary transition metal oxide/graphene composites as anode materials has been attracting more interest from researchers, based on the fact that binary transition metal oxides and graphene are expected to create a synergistic effect and exhibit improved lithium storage characteristics. In this work, a NiO-CuO/reduced graphene oxide composite (NiO-CuO/RGO) was prepared by an ultrasonic agitation process. When the NiO-CuO/RGO is applied to the anode material for lithium-ion batteries (LIBs), the batteries display high discharge capacities (at 730 mA h/g after 100 cycles at 100 mA/g), high-rate performance (311 mA h/g with 5000 mA/g), and excellent stable cyclability (375 mA h/g within 2000 mA/g after 400 cycles). Such results indicate that the combination of NiO-CuO and RGO leads to enhanced lithium storage performance, for the RGO sheets inhibit the large volume change of binary NiO-CuO and enhance the fast transport of both lithium ions and electrons during the repeated lithium cycling processes.

Facile Synthesis of Novel Short-Chain Ligand-Capped Colloidal Metal Oxide Nanoparticles for Printed Flexible Devices.

Colloidal metal oxide nanoparticles are key materials for achieving cost-effective and large-scale production of flexible devices, as they enable the formation of functional oxide thin films at low temperatures (<400 °C) through printing techniques such as inkjet printing, gravure coating, and microcontact printing. The conventional solvothermal synthesis of colloidal metal oxide nanoparticles through the thermal decomposition of precursors results in particles with bulky, long-chain ligands on their surfaces, which hinder the formation of dense oxide films when depositing the colloidal metal oxide nanoparticles. Herein, we have developed a simple and versatile method for synthesizing colloidal metal oxide nanoparticles using base-induced hydrolysis and the condensation of metal acetates as precursors. Various binary and ternary colloidal metal oxide nanoparticles (CuO, Mn3O4, Co3O4, CeO2, In2O3, Co1.8Mn1.2O4) were synthesized using short-chain acetate ligands on their surfaces. The thin acetate ligand-containing colloidal Co1.8Mn1.2O4 nanoparticle film exhibited lower resistivity than the same with long-chain oleate ligands. The films coated onto a polyimide substrate formed a flexible negative temperature coefficient thermistor that exhibited the temperature dependence of resistance comparable to bulk materials with a bending durability of up to 5 mm radius. These findings highlight the effectiveness of utilizing colloidal metal oxide nanoparticles with short-chain ligands in flexible devices.

Electrochemical evaluation of low crystalline CoFe2O4@Reduced graphene oxide nanocomposite for hybrid supercapacitor application

The development of high-performance and cost-effective energy storage materials remains of significant scientific interest. Here, low-crystalline (LC) binary transition metal oxide (BTMO) CoFe2O4 is studied for its application in a hybrid supercapacitor. This disordered LC CoFe2O4 material was prepared by the co-precipitation method, and to improve the electron transport property of the LC CoFe2O4, a composite was prepared with reduced graphene oxide (RGO). LC CoFe2O4@rGO interconnected network enhances the electrolyte ion diffusion within the material. This CoFe2O4@RGO shows an electrochemical performance of 2247.82 mF cm−2 at a current density of 1 mA cm−2. The cyclic stability study is performed to CF@RGO 20 % electrode for 2000 cycles at 30 mA cm−2 current density. Further, to understand the charge storage mechanism, Dunn analysis is done, the capacitive and diffusion contributions to charge storage are studied. Besides, the charge transfer and diffusion characteristics of the material were studied using electrochemical impedance spectroscopy. So, these LC CoFe2O4@RGO based materials with improved ion diffusivity and flexibility in synthesis make them attractive candidates for the development of high-performance and cost-effective supercapacitor.

Spinel cobalt-based binary metal oxides as emerging materials for energy harvesting devices: synthesis, characterization and synchrotron radiation-enabled investigation.

The synthesis and characterization of spinel cobalt-based metal oxides (MCo2O4) with varying 3d-transition metal ions (Ni, Fe, Cu, and Zn) were explored using a hydrothermal process (140 °C for two hours) to be used as alternative counter electrodes for Pt-free dye-sensitized solar cells (DSSCs). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed distinct morphologies for each metal oxide, such as NiCo2O4 nanosheets, Cu Co2O4 nanoleaves, Fe Co2O4 diamond-like, and Zn Co2O4 hexagonal-like structures. The X-ray diffraction analysis confirmed the cubic spinel structure for the prepared MCo2O4 films. The functional groups of MCo2O4 materials were recognized in metal oxides throughout Fourier transform infrared (FTIR) analysis. The local structure analysis using X-ray absorption fine structure (XAFS) at Fe and Co K-edge identified octahedral (Oh) Co3+ and tetrahedral (Td) Co2+ coordination, with Zn2+ and Cu2+ favoring Td sites, while Ni3+ and Fe3+ preferred Oh active sites. Further investigations utilizing the Fourier transformation (FT) analysis showed comparable coordination numbers and interatomic distances ranked as Co-Cu > Co-Fe > Zn-Co > Co-Ni. Furthermore, the utilization of MCo2O4 thin films as counter electrodes in DSSC fabrication showed promising results. Notably, solar cells based on CuCo2O4 and ZnCo2O4 counter electrodes showed 1.9% and 1.13% power conversion efficiency, respectively. These findings indicate the potential of employing these binary metal oxides for efficient and cost-effective photovoltaic device production.

Construction of 3D spinel binary metal oxide flower decorated 1D halloysite nanotube electrocatalyst for the selective detection of arsenic drug pollutant roxarsone

Heavy metals, including arsenic (As), are categorized as a Group I toxic carcinogen and pose significant threats to the environment and habitats. Roxarsone (RXN) is an organoarsenic antibiotic drug commonly employed as a veterinary curative agent and growth promoter for poultry. Due to its widespread use, it substantially contributes to the accumulation of As in humans and ecosystems. Therefore, it is essential to monitor this potential drug in various real-world samples with high accuracy. Consequently, we have designed 3D zinc cobalt oxide (ZCO) with a 1D halloysite nanotube (HNT) based electrochemical sensor. The functional and morphological features of the electrocatalysts were evaluated with numerous analytic methods. The electrocatalytic property was investigated with different voltammetric measurements. Based on the outcomes, our ZCO/HNT-modified sensor displayed good linear ranges (0.01 to 127 μM and 127 μM to 1147 μM), low detection (1.6 nM), and quantification (5.2 nM) limits, optimal sensitivity (0.465 μA μM−1 cm−2), good selectivity, remarkable performance, and good stability results. Further, this sensor was applied to monitor RXN in various real-world samples and consequently, obtained the well-resolved results. Hence, our ZCO/HNT is an efficacious electrocatalyst for the precise detection of RXN.

Facile synthesis of porous ZnCo2O4 micro–flower decorated with SWCNTs toward superior lithium storage performance

Binary metal oxides ZnM2O4 (A = Co, Fe, Mn) with spinel structures have been widely studied for their high theoretical specific capacity, relatively low cost, controllable morphology and synergistic effect between metal oxides with different charging and discharging mechanisms. However, the electrochemical properties are seriously affected by the huge volume change during cycles and poor electronic conductivity. In this work, porous ZnCo2O4 micro–flowers self–assembled from nano–sheets are successfully prepared by a simple solvothermal method followed by a heat treatment process without the aid of any soft/hard templates, and the resulting ZnCo2O4 active material is further decorated with SWCNTs. The phase composition, morphology characteristic, specific surface area, pore size distribution, elemental valence state and other information of the as–prepared samples are analyzed by relevant techniques such as XRD, FTIR, FESEM, (HR)TEM, TGA, Raman, N2 adsorption/desorption measurement and XPS. As anode materials in Li–ion batteries, the ZnCo2O4/SWCNTs product exhibits high charge/discharge specific capacity, excellent cycling stability and remarkable rate capability. Excellent electrochemical performance benefits from the special micro–/nano–structure characteristics of the as–synthesized ZnCo2O4/SWCNTs electrode material and good dynamic characteristics during cycling.

First Principles Calculations of Novel Binary Transition Metal Oxides NaCr0.5X0.5O2 (X = Y, Tc, Rh) for Na-Ion Batteries

Recently, layered transition metal oxides have demonstrated voltage windows favorable for use as cathodes in sodium-ion batteries, leading to increased specific capacity and energy density. Here, NaCr0.5Y0.5O2, NaCr0.5Tc0.5O2, and NaCr0.5Rh0.5O2 were studied by using first-principles calculations to elucidate their properties. There is a trigonal arrangement in the structure of both pure and substituted NaCrO2. Structural characteristics reveal the ferromagnetic behavior of these compounds (NaCr0.5X0.5O2; X = Y, Tc, Rh). We calculated the density of states and spin-polarized electronic band structures for the three compounds tested. NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2 exhibit diluted magnetic semiconductor (DMS) behavior, while NaCr0.5Tc0.5O2 has half-metallic (HM) behavior. The substitutional material’s ferromagnetic nature is confirmed by the negative values of the exchange constants (Nօ α and Nօ β). The fractional value of the magnetic moment also confirms the DMS nature of NaCr0.5Y0.5O2 and NaCr0.5Rh0.5O2, while the HM behavior is confirmed by the integral value of the magnetic moment for NaCr0.5Tc0.5O2. The thermoelectric characteristics were computed using the BoltzTraP code. Alectrochemical analysis of NaCr0.5Y0.5O2 showed a theoretical discharge capacity of 400 mhAg−1 and an average intercalation voltage of 4.87 V, calculated from the total energies of the optimized compounds and their de-sodianted phases. These theoretical computations demonstrate that the binary layered TM oxides studied are appropriate substances to employ in coin cell fabrication as cathodes.

Carbon nanotube reinforced FeMoO4 nanorods as a high-performance anode for sodium-ion batteries

Iron molybdate (FeMoO4) nanostructures show great promise as a superior anode for sodium-ion batteries. However, its use in practical application is hampered by its poor electronic conductivity, large volume changes and sluggish reaction kinetics. Herein, we have developed an interconnected network of multiwall carbon nanotube (CNT) and FeMoO4 (FMO) by a simple one-step hydrothermal method. As well as providing efficient channels for charge transfer and diffusion, highly conductive CNTs also have a degree of volume elasticity and excellent electrical conductivity to ensure migration of sodium ions, enabling both fast kinetics and long-term stability. As a result, the FMO@CNT anode delivers a high reversible capacity of 485 mA h g−1 at 0.05 A/g and very long cycling stability with a capacity of 75 mA h g−1 after 1000 cycles at 1 A/g. Furthermore, by combining the ex-situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy and cyclic voltammetry results, sodium ion storage mechanism of the FMO@CNT electrode obeys a conversion mechanism. The results of this work provide a better understanding on the sodium ion storage mechanism of binary metal oxides.

Nanostructured binary transition-metal-sulfides and nanocomposites as high-performance electrodes for hybrid supercapacitors

Supercapacitors (SCs) are attractive as promising energy storage devices because of their distinctive attributes, such as high power density, good current charge/discharge ability, excellent cyclic stability, reasonable safety, and low cost. Electrode materials play key roles in achieving excellent performance of these SCs. Among them, binary transition metal sulfides (BTMSs) have received significant attention, attributed to their high conductivity, abundant active sites, and excellent electrochemical properties. This topic review aims to summarize recent advances in principles, design, and evaluation of the electrochemical performance for nanostructured BTMSs (including nickel–cobalt sulfides, zinc–cobalt sulfides, and copper–cobalt sulfides.) and their nanocomposites (including those carbon nanomaterials, transition metal oxides, binary transition metal oxides, transition metal sulfides, and polymers). Nanostructuring of these BTMSs and nanocomposites as well as their effects on the performance were discussed, including nanoparticles, nanospheres, nanosheets, nanowires, nanorods, nanotubes, nanoarrays, and hierarchitectured nanostructures. Their electrochemical performance has further been reviewed including specific capacitance, conductivity, rate capability, and cycling stability. In addition, the performance of hybrid supercapacitors (HSCs) assembled using the nanostructured BTMSs as the cathodes also have been summarized and compared. Finally, challenges and further prospects in the HSCs-based BTMS electrodes are presented.

Para-Nitrophenol detection by an electrochemical approach based on two-dimensional binary metal oxides ZrO2-Nd2O3 nanorod fabricated with PEDOT:PSS onto glassy carbon electrode

In this approach, a wet chemical method was employed to synthesize the nanorods (NRs) of Zirconium oxide − Neodymium Oxide (ZrO2-Nd2O3) in an aqueous solution. Comprehensive characterizations encompassing ultraviolet/visible diffuse reflectance spectroscopy (UV/vis DRS), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), alongside field emission scanning electron microscopy (FESEM) equipped with X-ray energy-dispersive spectroscopy (EDS), were applied for optical, elemental, morphological, and structural analyses of resultant material. To fabricate a highly selective and ultra-sensitive electrochemical sensor for para-Nitrophenol (para-NP) in the presence of other interfering toxic chemicals, a glassy carbon electrode (GCE) was modified with a thin layer of ZrO2-Nd2O3NRs. Poly 3,4-ethylenedioxythiophene polystyrene sulfonate (PEDOT:PSS) served as an adhesive conducting binder in this modification process. Subsequently, we introduced a novel electrochemical approach for the first time for the detection of para-NP by making use of newly developed ZrO2-Nd2O3-NRs/PEDOT:PSS/GCE as selective para-NP electrochemical sensor in an aqueous medium. This innovative electrochemical approach exhibited remarkable electrochemical responses, featuring high sensitivity and long-term stability when applied to para-NP detection. The calibration curve demonstrated linearity across broad linear dynamic range (LDR) spanning para-NP concentrations from 0.1 pM to 0.1 mM. Key analytical parameters, including limit of detection (LOD) at signal-to-noise ratio (SNR) of 3, limit of quantification (LOQ), and sensitivity, were determined to be 0.0141 pM, 0.047 pM, and 0.67 μAμM-1cm−2, respectively, based also on the gradient of calibration plot. This sensor holds significant promise for real sample analysis aimed at preserving the natural environment. So, this study introduces a novel and well-structured approach to the development of a highly sensitive para-NP sensor utilizing ZrO2-Nd2O3-NRs/PEDOT:PSS/GCE, employing a reliable electrochemical approach.

Enhanced Energy Storage Performance through Controlled Composition and Synthesis of 3D Mixed Metal-Oxide Microspheres.

Binary transition metal oxide complexes (BTMOCs) in three-dimensional (3D) layered structures show great promise as electrodes for supercapacitors (SCs) due to their diverse oxidation states, which contribute to high specific capacitance. However, the synthesis of BTMOCs with 3D structures remains challenging yet crucial for their application. In this study, we present a novel approach utilizing a single-step hydrothermal technique to fabricate flower-shaped microspheres composed of a NiCo-based complex. Each microsphere consists of nanosheets with a mesoporous structure, enhancing the specific surface area to 23.66 m2 g-1 and facilitating efficient redox reactions. When employed as the working electrode for supercapacitors, the composite exhibits remarkable specific capacitance, achieving 888.8 F g-1 at 1 A g-1. Furthermore, it demonstrates notable electrochemical stability, retaining 52.08% capacitance after 10,000 cycles, and offers a high-power density of 225 W·kg-1, along with an energy density of 25 Wh·kg-1, showcasing its potential for energy storage applications. Additionally, an aqueous asymmetric supercapacitor (ASC) was assembled using NiCo microspheres-based complex and activated carbon (AC). Remarkably, the NiCo microspheres complex/AC configuration delivers a high specific capacitance of 250 F g-1 at 1 A g-1, with a high energy density of 88 Wh kg-1, for a power density of 800 W kg-1. The ASC also exhibits excellent long-term cyclability with 69% retention over 10,000 charge-discharge cycles. Furthermore, a series of two ASC devices demonstrated the capability to power commercial blue LEDs for a duration of at least 40 s. The simplicity of the synthesis process and the exceptional performance exhibited by the developed electrode materials hold considerable promise for applications in energy storage.

In-situ synthesis of coral reef-like synergistic zinc cobalt oxide and zinc manganese oxide composite as a battery-type electrode material for supercapacitors

Recently, in-situ preparation of metal oxide composite structures has gained much importance in fabricating electrode materials for energy storage and conversion devices because of its advantageous properties of beneficial interfacial contact, high conductivity, good synergism, short ion diffusion distance, better electrochemical performance, etc. Binary transition metal oxides (BTMOs) are given great attention for their significant electrochemical performances over primary MOs because of the two metal ions with different valent states for the redox reactions. In this study, we synthesize zinc cobalt oxide (ZnCo2O4) and zinc manganese oxide (ZnMn2O4) composite via a solvothermal synthetic method. The existence of both phases is identified using an X-ray diffraction analysis (XRD). The unique coral reef-like structures of the composite electrode are analysed via field emission scanning electron microscopy, and the nanostructure was identified using transmission electron microscopy. The X-ray photoelectron spectroscopy confirms the surface oxidation states of the composite and supports the XRD analysis. The synergetic composite electrode provides a large surface area of 50.86 m2 g−1 with many pores. The composite electrode has a specific capacity of 250 C g−1 at 1 A g−1. The ZCO/ZMO composite demonstrated impressive stability, retaining a specific capacity of 180 C g−1 at 6 A g−1 over 5000 cycles.

Spin-selective evolution of the Zhang-Rice state in binary transition metal oxide MnO(001) film

Spin-selective evolution of the Zhang-Rice state in binary transition metal oxide MnO(001) film

Production of green hydrogen through PEM water electrolysis

Abstract The need for abundant, sustainable, and clean energy is becoming increasingly important in the modern world due to continuous population growth and industrial expansion. Hydrogen (H2) has been identified as a potential energy carrier due to its high gravimetric energy density. Because H2 is not frequently found in its molecular form, it has to be obtained through various methods such as steam methane reforming, coal gasification, fossil fuels, and electrochemical techniques. H2 produced via PEMWE has proved to be an efficient method compared to other electrolysers. The limiting factor of a PEM electrolyser system is the OER catalyst. Commercially, IrO2 and RuO2 are used; however, both these metals are rare and expensive. Current research reports the use of binary metal oxides as an alternative OER catalyst to decrease the overall CAPEX costs. Various synthesis methods are available, with the Adams’ fusion method being the simplest. Characterisation techniques used to evaluate the performance of these catalysts include cyclic voltammetry (CV), linear scan voltammetry (LSV), XRD, XRF, SEM/EDS, and chronopotentiometry. Hydrogen as a clean fuel has a broad potential for use across all sectors, including transportation, residential, and industrial. In recent years, extensive research has been done on all aspects of hydrogen production, storage, and transportation. This review paper aims to study other bimetallic metals to reduce the Ir content used as an oxidative evolution reaction to reduce the capital cost of the PEM electrolyser. To produce green hydrogen that could reduce the carbon footprint in several industrial processes.

Extraordinary synergy on 3D hierarchical porous Co-Cu nanocomposite for catalytic elimination of VOCs at low temperature and high space velocity

It is still a challenge to develop hierarchically nanostructured catalysts with simple approaches to enhance the low-temperature catalytic activity. Herein, a set of mesoporous Co-Cu binary metal oxides with different morphologies were successfully prepared via a facile ammonium bicarbonate precipitation method without any templates or surfactants, which were further applied for catalytic removal of carcinogenic toluene. Among the catalysts with different ratios, the CoCu0.2 composite oxide presented the best performance, where the temperature required for 90% conversion of toluene was only 237°C at the high weight hour space velocity (WHSV) of 240,000 mL/(gcat·hr). Meanwhile, compared to the related Co-Cu composite oxides prepared by using different precipitants (NaOH and H2C2O4), the NH4HCO3-derived CoCu0.2 sample exhibited better catalytic efficiency in toluene oxidation, while the T90 were 22 and 28°C lower than those samples prepared by NaOH and H2C2O4 routes, respectively. Based on various characterizations, it could be deduced that the excellent performance was related to the small crystal size (6.7 nm), large specific surface area (77.0 m2/g), hollow hierarchical nanostructure with abundant high valence Co ions and adsorbed oxygen species. In situ DRIFTS further revealed that the possible reaction pathway for the toluene oxidation over CoCu0.2 catalyst followed the route of absorbed toluene → benzyl alcohol → benzaldehyde → benzoic acid → carbonate → CO2 and H2O. In addition, CoCu0.2 sample could keep stable with long-time operation and occur little inactivation under humid condition (5 vol.% water), which revealed that the NH4HCO3-derived CoCu0.2 nanocatalyst possessed great potential in industrial applications for VOCs abatement.

Enhanced fluoride removal using Mg-Zr binary metal oxide nanoparticles confined in a strong-base anion exchanger

Generally, the pH of fluorinated groundwater or many industrial wastewater is neutral, while the majority of metal-modified adsorbents can work efficiently only under acidic conditions. In this study, we synthesized a novel hybrid adsorbent, Mg–Zr-D213, by loading nano-Mg/Zr binary metal (hydrogen) oxides in a strong-base anion exchanger, D213, to enhance the adsorption of fluoride from neutral water. Mg–Zr-D213 exhibited a better fluoride-removal capacity in neutral water than monometallic modified resins. Under the interference of competing anions and coexisting organic acids, Mg–Zr-D213 exhibited superior selectivity. The Langmuir model indicated that the fitted maximum sorption capacity of Mg–Zr-D213 was 41.38 mg/g. The results of column experiments showed that the effective treatment volume of Mg–Zr-D213 was 8–16-times higher than that of D213 for both synthetic groundwater and actual industrial wastewater, and that NaOH–NaCl eluent could effectively recover more than 95% of fluoride. Adsorption experiments with Mg/Zr metal (hydrogen) oxide particles and D213 separately demonstrated a synergistic effect between –N+(CH3)3 and Mg/Zr metal (hydrogen) oxide particles. The ligand exchange or metal-ligand interaction of Mg/Zr metal (hydrogen) oxide particles on fluoride was further demonstrated via X-ray photoelectron spectroscopy. Overall, Mg–Zr-D213 has great potential for enhanced fluoride removal in neutral water.

Carbamide-mediated facile sol-gel synthesis of porous flower-like ZnCo2O4 microspheres for high-performance asymmetric coin cell supercapacitors

The design and development of ultrahigh-performance nanomaterials possessing novel characteristics are needed to achieve reliable energy storage performance. To satisfy the needs, diverse electrode materials are explored. Even though carbon-based materials hold high surface area and conductivity, their specific capacitance value fails to deliver high-performance applications. Therefore, pseudocapacitive transition metal oxide is adopted to overcome these issues. Among all Zinc Cobaltite, a binary transition metal oxide is widely explored owing to its fascinating electrochemical properties. As most of the synthesis of these kinds of materials requires the hydro/solvothermal method, herein, we have proposed the concept of a facile sol-gel method to prepare this class of materials by using Carbamide as both structure director and fuel to achieve the porous flower-like Zinc Cobaltite. The prepared material delivers the notable gravimetric specific capacitance of 513.3 F g−1. Owing to its unique morphology and porous structure, ion channelization is feasible, which will enhance the electrochemical reaction. Constructed asymmetric coin cell supercapacitor showed an extraordinary specific capacitance of 106.5 F g−1 and energy density of 56.2 Wh kg−1, demonstrating an impressive ability to retain 89.6 % of its capacitance after 4000 cycles at a current density of 6 A g−1. Due to the remarkable electrochemical behavior, this work can act as a guiding tool for designing efficient and cost-effective energy storage devices that will hold prodigious potential in commercial energy storage applications.

A heterostructured ternary transition metal oxide composite as an efficient electrocatalyst for the hydrogen evolution reaction

A key method for hydrogen production is water electrolysis involving the oxygen and hydrogen evolution reactions. The efficiency of these processes is largely dependent on the use of effective electrode catalysts. Despite the high water-splitting catalytic activity of noble metals such as Pt, Ru, and Ir, their scarcity and costliness pose significant challenges. Although Fe and Fe-based compounds have recently been identified as promising alternative catalysts due to their abundance, affordability, and low toxicity, particularly under the alkaline conditions required for the hydrogen evolution reaction, both can be reduced to unstable forms during the reaction. To address this, the focus of the present study is on developing a ternary transition metal oxide electrocatalyst comprising Ni, Fe, and Co oxides. Thereby, we leveraged the synergistic interactions among them to provide a heterogeneous electrocatalyst for the hydrogen evolution reaction with a sufficiently low overpotential of 45 mV and suitably high Tafel kinetics of 44.99 mV dec−1 and long-term stability. The ternary transition metal oxide electrode showcased superior performance compared to one comprising binary transition metal oxides by achieving a lower overpotential and a better Tafel slope while maintaining catalytic stability even for 100 h at a current density of 1000 mA cm−2. This innovative approach offers a highly efficient alternative catalyst to Fe, which is known to have stability issues for hydrogen production, especially at high current density.