Nickel Foam Electrode Research Articles

In-situ synthesis of bifunctional N-doped CoFe₂O₄/rGO composites for enhanced electrocatalysis in hydrogen and oxygen evolution reactions

The development of cost-effective and efficient materials for electrochemical water splitting using non-noble metal oxide is a promising strategy to promote clean energy and mitigate environmental issues. In this study, we synthesized N-doped CoFe2O4 (NCF) and various wt% rGO-loaded N-doped CoFe2O4 (x = 1 %, 3 %, and 5 %; denoted as NCFRx) using a hydrothermal method. Subsequently, the NCF and NCFR3 samples were annealed at four different temperatures (y = 550, 600, 650, and 700 °C; denoted as NCFR3-y). FE-SEM, TEM, and XPS studies revealed a strong interface between rGO nanosheets and N-doped CF, acting as electron transport carriers that enhance performance in hydrogen and oxygen evolution reactions (HER and OER). The electrochemical evaluation of the prepared materials was carried out in a 1.0 M KOH electrolyte. The nickel foam (NF) electrode supported by the NCFR3–650 composite demonstrated excellent and stable electrocatalytic performance with a minimum overpotential of 73 mV and 170 mV at a current density of 10 mA/cm2 for HER and OER, respectively, and achieved excellent faradaic efficiencies of 91.01 % for OER and 90.48 % for HER. These results confirmed that the NCFR3–650@NF composite catalyst was comparable to standard Pt/C and IrO2, exhibiting lower overpotential and Tafel slope at a current density of 10 mA/cm2. The double layer capacitance (Cdl) of NCFR3–650@NF (7.70 mF/cm2) was higher than that of other electrocatalysts, indicating a large electrochemically active surface area. The structural properties of NCFR3–650@NF contributed to improved stability during long-term HER and OER analysis. Therefore, the developed NCFR3–650@NF electrocatalyst is a promising alternative to noble metal-centered systems for water splitting, offering overall high efficiency.

NiO nanolayer electrodeposited with Cobalt and Phosphide as a novel supercapacitor with high areal capacitance

In the present work, a novel supercapacitor electrode is fabricated via a two-step synthesis procedure. A NiO nanolayer was initially fabricated on a nickel foam electrode using hydrothermal synthesis to obtain a substrate with a high electrocatalytic area and good adhesive properties. Subsequently, the NiO-decorated nickel foam (NF) was employed as a substrate for the electrodeposition of cobalt and phosphorous. Morphological, structural, and surface characterization, along with various electrochemical tests, were conducted to gain insight into structure-property relationships. The as-prepared electrode (CoP@NF) exhibited excellent electrochemical behavior with an ultra-high areal capacitance of 3340 mF cm−2 at 5 mA cm−2 and high capacitance values even at high current densities. The exceptional electrochemical behavior can be attributed to the morphological and electronic modifications induced by aliovalent doping and the synergetic effect between the different electrode counterparts.

Gold nanoparticles-amplified laccase-based electrochemical biosensor using graphitized carbon@boron carbide as electron transfer promoter

A novel laccase-based electrochemical biosensor was developed based on graphitized carbon coated boron carbide (GC@B4C) particles and gold nanoparticles (AuNPs) as electron transfer promoter and signal amplifier, respectively. AuNPs were in-situ electrodeposited on nickel foam (NF) electrode, and chitosan was used to immobilize laccase (Lac) and GC@B4C particles on AuNPs/NF electrode. The fabricated Lac/GC@B4C/AuNPs/NF electrode showed excellent electrocatalytic activity and good electron transfer kinetics for catechol (CC) oxidation. In addition, Lac/GC@B4C/AuNPs/NF electrode exhibited wide linear range (0.1–500 µM), high sensitivity (157.3 µA mM−1), low detection limit (25 nM), desirable selectivity, favorable stability and satisfactory reproducibility for CC detection. This work provided new idea for the construction of laccase-based electrochemical biosensors.

Hierarchical MnCo2O4@MnWO4 core-shell nanoarrays on Ni foam as binder-free electrode for asymmetric supercapacitors

Supercapacitors (SCs) are generally perceived as competitive possibilities for portable electronic products due to their exceptionally high power density and extended operational lifespan. Nevertheless, the relatively low energy density remains a crucial obstacle to its widespread application. A hierarchical MnCo2O4@MnWO4 core-shell nanoarrays on nickel foam (NF) was designed and synthesized by utilizing the MnCo2O4 nanosheet array as the backbone and the MnWO4 nanosheet array as the shell via hydrothermal procedure and calcination. The MnCo2O4@MnWO4/NF electrode achieves 1428.5 F g−1 at 1 A g−1 with 97.8 % of its pristine capacity after 4000 cycles. The superior energy storage characteristic is a result of several factors, including the binder-free integrated electrode design, the synergistic effect between MnCo2O4 and MnWO4, and abundant active sites. The assembled asymmetric supercapacitor (ASC) has an energy density of 36.46 Wh kg−1 at 750 W kg−1, and 85.4 % capacity reserved after 5000 cycles.

Enhanced selectivity of reactive intermediates by modifying electrodes with layered materials for the green high-salinity wastewater treatment

Improving the selectivity of the reactive intermediates such as ClO− and •OH by modifying nickel foam electrodes with ion exchangeable layered materials would greatly enhance the efficiency of high-salinity wastewater treatment. A universal pattern was verified herein that through functioning as a permeable overlayer regulating the transport of cations/anions, ClO− and •OH could be the predominant intermediates in the anionic/cationic layered material modified electrode. The significance of selectivity enhancement includes improving electrochemical efficiency and reducing the usage of chemical reagents. For instance, it is demonstrated that electrochemically degrading high salinity azo wastewater using decorated electrodes would be as effective as chemical treatment. Furthermore, electrochemical oxidation using cation layered material modified electrode could reduce the pKa of the oxidized cellulose filter paper as effectively as using H2O2.

Eco-Friendly Electrochemical Sensor for Accurate Soil Nitrate Detection using ZnOx/PANI Nanocomposite on Nickel Foam Electrode

This study presents an innovative approach to enhancing nitrate detection in soil, a critical macronutrient for agriculture. We developed a novel electrochemical sensor using a nanocomposite of Zinc Oxide (ZnOx) and Polyaniline (PANI) on a Nickel foam electrode. The nanocomposite was synthesized through cyclic voltammetry and characterized using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), and X-ray Diffraction (XRD) to analyze its morphological, elemental, and crystalline properties. The sensor's performance was evaluated using square wave voltammetry, revealing a direct linear relationship between the peak current and nitrate concentration. The sensor demonstrated high sensitivity (4.53 µA/µM) and a low detection limit (0.40 µM), confirming its potential for precise and sensitive nitrate analysis in soil samples.

Core-shell structured MgCo2O4@Ni(OH)2 nanorods as electrode materials for high-performance asymmetric supercapacitors

In the field of energy storage, supercapacitors have received extensive attention in recent years. However, achieving the expected electrochemical performance and energy density of supercapacitors is still a huge challenge. The design and synthesis of binder-free composite electrode with core–shell structure is an effective strategy to improve the electrochemical performance of supercapacitors. In this paper, a heterogeneous core–shell structured and binder-free electrode material MgCo2O4@Ni(OH)2 (MCO@NH) grown on nickel foam (NF) is prepared by a simple hydrothermal and oil bath method. The unique core–shell structure makes the MCO@NH have a large specific surface area, which provides abundant active sites for ion transport and storage, thereby improving the electrochemical performance. The MCO@NH/NF nanocomposite demonstrates a high specific capacitance (Cs) of 1583 F g−1 at 1 A/g. A solid-state asymmetric supercapacitor (ASC) assembled with MCO@NH/NF and active carbon (AC) exhibits excellent energy density (45 Wh kg−1 at 457.5 W kg−1) and outstanding capacitance (89.51 %) and coulombic efficiency (97.8 %) after 12,000 cycles, evidencing its good operation stability and potential practical applications. Therefore, the prepared core–shell MCO@NH/NF electrode can be a promising candidate for energy storage devices.

Simple generic self-assembly fabrication of transition metal borates on polyaminophenylboric acid modified foam nickel for highly-efficient overall water splitting

Water electrocatalysis for hydrogen production as a prospect strategy to store renewable energy and reduce carbon emissions has attracted great attention, and exploring water electrolysis catalysts has become a research hotspot for widespread industrial water electrolysis application. Very recently, transition metal borates have been demonstrated great potential for electrocatalytic hydrogen or oxygen evolution in alkaline media. However, a generic method for fabricating transition metal borates as bifunctional oxygen catalysts are still challenging. Herein, through a two-step process including poly-aminophenylboronic acid electrodeposition and subsequent electrostatic self-assembly of transitional metal ions, for the first time, to our best knowledge, a simple and generic approach to fabricate polyaminophenylborate transition metal salt modified nickel foam electrodes (PAB-M/NF, M represents transition metal element) was developed for highly efficient water splitting. As a proof of concept, the obtained PAB-Ru/NF exhibited remarkable bifunctional HER and OER catalytic activities and stability in alkaline medium. To drive the HER and OER with a current density of 10 mA cm−2 in 1 M KOH electrolyte, PAB-Ru/NF only required an overpotential of 14 mV and 301 mV, respectively. Moreover, even at a great current density of 250 mA cm−2, PAB-Ru/NF can exhibit very favorable long-term stability for over 35 h. When assembled into an electrolyzer with PAB-Ru/NF as both the anode and cathode, a current density of 10 mA cm−2 can be achieved at a very low cell voltage of 1.50 V. In addition, the other PAB-M/NF catalysts (M including but not limited to Fe, Co and Ni) prepared by the same way also show excellent bifunctional HER and OER catalytic activities and durability. This study provides a prospective and economically feasible generic approach for developing practical bifunctional catalysts for industrial water electrolysis.

One-pot synthesis of tungsten oxynitride/nitrogen-doped graphene with particle-sheet hybrid nanostructure as a highly effective binder-free supercapacitor electrode

High-performance nanoscale composites have achieved predominance as promising materials for supercapacitor applications. Graphene nanosheets decorated with transition metal oxynitride nanoparticles can be highly beneficial in improving supercapacitor properties. However, they are hardly retrieved, and their electrochemical characterizations and inherent charge-storage mechanisms have not been deeply investigated. Herein, tungsten oxynitride decorated nitrogen-doped graphene (WON-NG) is synthesized by a facile one-pot strategy in a particle-sheet hybrid nanostructure. The nanocomposite is grown directly on a nickel foam (NF) as the current collector through the synthesis process. X-ray photoelectron spectroscopy and TEM images have confirmed the particle-sheet hybrid nanostructure of the prepared nanocomposite with tungsten oxynitride nanoparticles and nitrogen-doped graphene nanosheet. The oxygen and nitrogen-based redox groups, which synergistically coexist in the hybrid network, inherently cooperate in the electrochemical activities of the nanocomposite. The electrochemical measurements show that the WON-NG|NF electrode can deliver a superior specific capacitance of 1079.4 F g−1 (4.6 F cm−2) at 1 A g−1 in 1 M KOH aqueous electrolyte. In-depth investigations suggest that the diffusive-controlled process governs the charge storage mechanism at all scan rates in the composite for the advantageous porous morphology. The assembled all-solid-state asymmetric supercapacitor device exhibits a high energy density of 81.6 Wh kg−1 and a power density of 5005.4 W kg−1. Also, the designed devise shows an excellent cycle life with 87.7% capacitance retention of 10,000 cycles.

Selective Oxidation of Ethanol on a Nickel Foam Electrode Followed by Aldol Condensation with Furfural to Produce Furan-2-Acrolein

Catalytic conversion of biomass derived molecules into chemicals with energy and industrial applications represents a promising and sustainable route to replace petroleum resources. Therein, furfuraldehyde is among the top 30 biomass derived chemicals defined by the Department of Energy with a wide range of applications. Furfuraldehyde can be easily produced from corncob and straw with an annual production of more than 200000 tons. Furfuraldehyde can be converted into chemicals with high economical value via hydrogenation, oxidation, reductive amination, decarbonylation, nitration, and condensation reactions. Electrosynthesis utilizes a potential or current to replace the redox reagents employed in conventional redox synthesis. In contrast to the tedious reaction and work up conditions required for conventional chemical synthesis, electrosynthesis is often easy and straightforward. Despite these advantages, electrosynthesis represents an under explored area with a vast number of potential applications. The focus of this work is the Aldol condensation of furfural with electrochemically generated acetaldehyde and propanal. Preliminary electrocatalysis experiments conducted in 250 mM KOH with nickel foam working electrode demonstrate 80-95% Faradaic Efficiency for the electrochemical step and nearly 50% conversion of furfuraldehyde. The substrate scope for the oxidative Aldol condensation, optimization of reaction conditions and potential applications of thus formed Aldol products will be discussed in this presentation.

MnCo2O4 Spinel & Carbon Black coated Nickel Foam Electrode. A Bifunctional Water-Splitting Catalyst?

Hydrogen has the potential to revolutionise how we produce and consume energy. We can meet energy demands without compromising the environment by using renewable sources such as wind, solar and wave power producing low-cost electricity to split the water molecule into its constituent parts. We could then convert Hydrogen back to electricity using a fuel cell, as illustrated in Figure 1. The by-product in this entire process is water, giving a clean technology with no toxic or greenhouses gases. Currently the best performing electrocatalytic materials for water splitting are noble metal based, namely platinum for the hydrogen evolution reaction (HER) and Ruthenium for the oxygen evolution reaction (OER). The use of these materials is unsustainable and makes fuel cells too expensive for commercial applications. We must engineer sustainable, cost-effective alternatives.Nickel foam electrodes display desirable electrocatalytic properties such as a large surface area compared to volume with highly conducting, porous networks, while transition metal dichalcogenides show very good electronic properties with high surface areas and large active sites. In this work we show that it is possible to electrochemically and solvothermally produce CoSex and CoSex composites on a porous nickel foam electrode (NFE). The best performing materials were selected and evaluated via electrochemical impedance spectroscopy. This analysis showed high electrochemical active surface area (ECSA) values and good stability across the selected materials. Scanning electron microscopy (SEM) images reveal that the surfaces of the synthesized materials exhibit distinct morphologies and have been significantly modified. Further electrochemical evaluation of the materials reveals low overpotentials for both hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) thus showing promise as a potential bi-functional electrocatalyst in overall water splitting.References(1) Chaudhari, N. K.; Jin, H.; Kim, B.; Lee, K. Nanostructured Materials on 3D Nickel Foam as Electrocatalysts for Water Splitting. Nanoscale. 2017. https://doi.org/10.1039/c7nr04187j.(2) Minadakis, M. P.; Tagmatarchis, N. Exfoliated Transition Metal Dichalcogenide-Based Electrocatalysts for Oxygen Evolution Reaction. Advanced Sustainable Systems. 2023. https://doi.org/10.1002/adsu.202300193.(3) Sukanya, R.; da Silva Alves, D. C.; Breslin, C. B. Review—Recent Developments in the Applications of 2D Transition Metal Dichalcogenides as Electrocatalysts in the Generation of Hydrogen for Renewable Energy Conversion. J Electrochem Soc 2022, 169 (6). https://doi.org/10.1149/1945-7111/ac7172. Figure 1

PFAS-Free: Robust and Chemically Stable Ion-Solvating Polymer Membrane Derived from Poly(arylene alkylene) for High-Performance Alkaline Water Electrolysis

Polymeric ion-solvating membranes1 derived from poly(arylene alkylene)s2 have emerged as promising candidates for alkaline water electrolysis, offering a PFAS-free, robust, and chemically stable alternative. This work focuses on the development of such a membrane with an emphasis on high resistance to gas crossover, addressing the challenges associated with conventional ion-exchange materials.The polymer membrane presented in this study demonstrated very good performance in alkaline water electrolysis. At 80 degrees Celsius, the membrane exhibits a specific conductivity of 36 mS/cm, underscoring its ion-solvating ability and efficiency in a 20 wt% KOH solution. The electrochemical performance is exemplified by the attainment of a 700-mA current below 2.6V with uncatalyzed nickel foam electrodes, showcasing the superior conductivity and efficiency in facilitating the electrolysis process.One of the key features of these membranes is their longevity, as evidenced by their ability to operate for more than 200 hours without any discernible voltage decay. This extended operational lifespan underscores the robustness and durability of the developed membranes, making them highly suitable for practical applications in alkaline water electrolysis.Furthermore, the membranes exhibit a high resistance to gas crossover, addressing a common challenge in electrolysis systems. This property ensures enhanced selectivity and efficiency by minimizing unwanted reactions and improving the overall electrolysis process.In conclusion, the presented work signifies a significant advancement in the development of ion-solvating polymer membranes derived from poly(arylene alkylene) for alkaline water electrolysis. The membranes not only outperform existing alternatives but also offer a sustainable and environmentally friendly solution by being PFAS-free. The demonstrated high performance, stability, and resistance to gas crossover make these membranes promising candidates for the advancement of alkaline water electrolysis technology, contributing to the development of efficient and environmentally conscious hydrogen production systems. Keywords: Alkaline; electrolysis; Poly (arylene alkylene)s; membranes; ion-solvating

Phytogenic Cu2OBi2O3ZrO2 nanomaterial for supercapacitor and water splitting: Synthesis, characterization, and energy applications

Copper-based nanocomposites are regarded as sustainable energy materials having tremendous potential for energy storage supercapacitors and energy generation water splitting applications. Herein, a facile Cu-based ternary Cu2OBi2O3ZrO2 nanocomposite is prepared by a sustainable, lower-cost, and simple hydrothermal-based phyto-synthesis route by using Amaranthus Viridis L. amaranthaceae plant (abbreviated as AVL.A). The synthesized AVL.A-Cu2OBi2O3ZrO2 nanocomposite is characterized by powder-X-ray diffraction and FE-Scanning electron microscopy for its phase composition and surface morphology. The electrochemical efficiency of AVL.A-Cu2OBi2O3ZrO2 nanocomposite is investigated for supercapacitors and overall water splitting. The fabricated Cu2OBi2O3ZrO2 nanocomposite-based Nickel foam (NF) electrode shows superior performance with a specific capacitance of 524.5 F/g at 2 mV/s and 400 F/g at 1 A/g. The excellent rate capability is observed at scan rates from 2 mv/s to 300 mV/s and at current densities from 0.5 A/g to 30 A/g for AVL.A-Cu2OBi2O3ZrO2–NF. Furthermore, fabricated AVL.A-Cu2OBi2O3ZrO2–NF shows excellent electrochemical stability with 100% Coulombic efficiency till 5000 charge-discharge cycles. As bifunctional electrocatalyst AVL.A-Cu2OBi2O3ZrO2–NF electrode exhibits 117 mV overpotential at 10 mA/cm2 current density for HER kinetics along with 112 mV/dec Tafel slope values. The same Tafel slope value is also observed for OER measurements. These values of overpotential and Tafel slope for AVL.A-Cu2OBi2O3ZrO2–NF suggest a rapid and efficient electrochemical process of AVL.A-Cu2OBi2O3ZrO2–NF bifunctional electrocatalyst for energy generation. Overall study highly proposed AVL.A-Cu2OBi2O3ZrO2–NF as the potential electrode for energy storage supercapacitor and energy generation overall water splitting.

(Sm3+/Eu3+/Tm3+)-TiO2 heterostructures for electrochemical and photovoltaic applications

This study reports on the synthesis of lanthanide oxides triply doped titania, forming a novel hetero-system known as (Sm3+/Eu3+/Tm3+)-TiO2. An environmentally friendly sol gel method was used to synthesize the energy-efficient (Sm3+/Eu3+/Tm3+)-TiO2, and thin films were deposited by spin coating. Electrode and solar cell devices were fabricated under ambient conditions, and rare earth doping enhanced the opto-electronic aspects of the host by narrowing the band gap up to 3.92, 3.85, and 3.56 eV. Particle sizes for the pure and doped materials were 85.15 and 82.72 nm, respectively. With a specific capacitance of 667.34 F g−1, the lanthanide-doped ornamented nickel foam electrode outperformed the pristine electrode, which had a specific capacitance of 169.59 F g−1. Moreover, this electrode exhibited tiny equivalent series resistance (Rs) of 0.13 Ω, indicating quicker response kinetics at the interface, in addition to its electrical double layer capacitance behavior. Electrochemical studies revealed that (Sm3+/Eu3+/Tm3+)-TiO2 semiconductor has a high specific power density of 8157.03 W kg−1, compared to 4079.73 W kg−1 for undoped titania. This improved specific power density demonstrates its suitability for practical scale applications. The produced materials were an excellent HER electro-catalyst with remarkably lower overpotential and Tafel slopes i.e., of 137 mV and 87.6 mV dec−1, in a respective manner, in comparison to the reference TiO2 with 147 mV and 104.5 mV dec−1, respectively. The electro-catalyst's response to the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) was enhanced upon lanthanide doping. Additionally, this substance successfully retrieved electrons from a perovskite solar cell device, achieving efficiency levels of 16.49 and 16.75 % in both forward and reverse bias with fill factor increase.

Exfoliated 2D Nanosheet-Based Conjugated Polymer Composites with P-N Heterojunction Interfaces for Highly Efficient Electrocatalytic Hydrogen Evolution.

We have achieved a significant breakthrough in the preparation and development of two-dimensional nanocomposites with P-N heterojunction interfaces as efficient cathode catalysts for electrochemical hydrogen evolution reaction (HER) and iodide oxidation reaction (IOR). P-type acid-doped polyaniline (PANI) and N-type exfoliated molybdenum disulfide (MoS2) nanosheets can form structurally stable composites due to formation of P-N heterojunction structures at their interfaces. These P-N heterojunctions facilitate charge transfer from PANI to MoS2 structures and thus significantly enhance the catalytic efficiency of MoS2 in the HER and IOR. Herein, by combining efficient sodium-functionalized chitosan-assisted MoS2 exfoliation, electropolymerization of PANI on nickel foam (NF) substrate, and electrochemical activation, controllable and scalable Na-Chitosan/MoS2/PANI/NF electrodes are successfully constructed as non-noble metal-based electrochemical catalysts. Compared to a commercial platinum/carbon (Pt/C) catalyst, the Na-Chitosan/MoS2/PANI/NF electrode exhibits significantly lower resistance and overpotential, a similar Tafel slope, and excellent catalytic stability at high current densities, demonstrating excellent catalytic performance in the HER under acidic conditions. More importantly, results obtained from proton exchange membrane fuel cell devices confirm the Na-Chitosan/MoS2/PANI/NF electrode exhibits a low turn-on voltage, high current density, and stable operation at 2 V. Thus, this system holds potential as a replacement for Pt/C with feasibility for applications in energy-related fields.

Structural Reconstruction of a Cobalt- and Ferrocene-Based Metal-Organic Framework during the Electrochemical Oxygen Evolution Reaction.

Metal-organic frameworks (MOFs) are increasingly being investigated as electrocatalysts for the oxygen evolution reaction (OER) due to their unique modular structures that present a hybrid between molecular and heterogeneous catalysts, featuring well-defined active sites. However, many fundamental questions remain open regarding the electrochemical stability of MOFs, structural reconstruction of coordination sites, and the role of in situ-formed species. Here, we report the structural transformation of a surface-grown MOF containing cobalt nodes and 1,1'-ferrocenedicarboxylic acid linkers (denoted as CoFc-MOF) during the OER in alkaline electrolyte. Ex situ and in situ investigations of CoFc-MOF film suggest that the MOF acts as a precatalyst and undergoes a two-step restructuring process under operating conditions to generate a metal oxyhydroxide phase. The MOF-derived metal oxyhydroxide catalyst, supported on nickel foam electrodes, displays high activity toward the OER with an overpotential of 190 mV at a current density of 10 mA cm-2. While this study demonstrates the necessity of investigating structural evolution of MOFs during electrocatalysis, it also shows the potential of using MOFs as precursors in catalyst design.

Improved rate capability and energy density of high-mass hybrid supercapacitor realized through long-term cycling stability testing and selective electrode design

To render supercapacitors (SCs) more practical, they must exhibit high cycling stability of at least ten thousand cycles with commercial-level mass loadings, which differentiates them from batteries. Metal-organic framework (MOF)-based electrode materials are promising for use in energy storage systems owing to their excellent electrochemical performance. In this study, we report the electroactivities of bimetallic MOFs (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, we develop a general strategy for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are investigated. Based on an analysis of the electrochemical properties of all the synthesized electrode materials, the optimal electrode delivers an ultrahigh areal capacity of 2621 µAh cm−2 (297.1 mAh g−1) at 7 mA cm−2, with a high-rate capability of 82.5 % even at 40 mA cm−2. The optimized Co–Ni MOF electrode is employed as a positive electrode to fabricate an aqueous hybrid SC (HSC) with an activated carbon-coated nickel foam electrode as a negative electrode. The as-fabricated HSC exhibits excellent electrochemical properties with exceptional cycling stability (120k cycles) and improved rate capability (60 %). Additionally, we identify factors that contribute to improved redox reactions in the Co–Ni MOF-based HSC, such as the role of Co–Ni MOFs in the redox reaction and the influences of other structural parameters on charge storage and transfer processes. Our aim is to further understand the underlying mechanisms of the improved redox reactions and thus obtain new insights into the design and optimization of Co–Ni MOF-based HSCs. Finally, the energy storage properties of the HSC are validated by using it to power different electronic devices. The promising outcomes obtained in this work can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates. SynopsisTo render the practicability of hybrid supercapacitor (HSC) with enhanced energy storage properties, we investigate the electroactivities of bimetallic metal-organic frameworks (MOFs) (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, a general strategy is developed for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are studied. In addition, we validate the energy storage properties of the HSC by using it to power different electronic devices. The promising outcomes obtained in this study can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates.

Rational Construction of Bi2CuO12Se4 and VGCFs@Fe2O3 Composite Electrodes for High-Performance Semi-Solid-State Asymmetric Supercapacitors.

Recently, supercapacitors (SCs) are extensively explored as effective energy storage devices. Specifically, asymmetric SCs are being developed to enhance energy density using suitable materials with favorable nanostructures. This study describes the construction of a bismuth copper selenite (BCS-200) working electrode with an ultrathin nanosheet(UTNS) architecture. This morphology is achieved using a low-cost electrodeposition (ED) method, followed by annealing. The impact of ED time on the development of morphology is studied by synthesizing comparative electrodes simultaneously. The optimized BCS-200 electrode prepared with a deposition time of 200 s shows higher specific capacity/capacitance (Cs/Csc) values of 330.9 mAh g-1/2206.6 F g-1 than the other synthesized electrodes (BCS-100, BCS-150, BCS-250, and BCS-300). Besides, a vapor-grown carbon fiber (VGCF)-added Fe2O3 composite coated on nickel foam (NF) is developed as a negative electrode. The VGCFs@Fe2O3/NF electrode exhibits the (Cs/Csc) values of 183.5 mAh g-1/734.4 F g-1, which is associated with ultra-high cycling stability. In addition, the fabricated BCS-200 and VGCFs@Fe2O3/NF electrodes are combined to construct a wearable semi-solid-state asymmetric SC (SSASC) with an energy density (Ed) of 20.5Wh kg-1 and a cycling stability of 91.7% over 40000 charge/discharge cycles. Furthermore, the real-time applicability of the SSASC is verified by powering it in practical applications.

Manganese-decorated CoP@CoFe2O4 nanorod arrays for high-efficiency alkaline water oxidation

Regulating the intrinsic activity of electrocatalysts is an effective strategy towards outstanding behaviour for oxygen evolution reaction (OER). Herein, the rational design of a Mn–CoP@CoFe2O4 core-shell heterojunction using nickel foam (NF) as a supporting material with special interface engineering has been investigated by a facile hydrothermal technique combined with phosphorization and electrodeposition method. The physical characterization demonstrates Mn–CoP@CoFe2O4 core-shell heterostructure with Mn–CoP nanoneedles as core and CoFe2O4 nanosheets as shell has been successfully acquired. The electrochemical measurements of the as-prepared Mn–CoP@CoFe2O4/NF core-shell heterojunction nanoarray electrode exhibit the superior electrocatalytic behaviour for OER (Tafel slope of 35.6 mV dec−1 and overpotential of 209.6 mV@10 mA cm−2). The remarkable OER behaviour may be ascribed to the sufficient active sites and the enhanced intrinsic activity due to the introduction of CoFe2O4 and Mn element, which can regulate the electron structure and increase the turnover frequency. Furthermore, the Mn–CoP@CoFe2O4/NF electrode appears an excellent long-run stability during the OER process at 100 mA cm−2 for 100 h. Therefore, the construction of metal doping transition metal-based core-shell heterostructure electrocatalysts may be a promising way for the remarkable OER electrocatalytic performance towards water splitting.

CuFe2O4 Nanofiber Incorporated with a Three-Dimensional Graphene Sheet Composite Electrode for Supercapacitor and Electrochemical Sensor Application

The demand for regenerative energy and electric automotive applications has grown in recent decades. Supercapacitors have multiple applications in consumer alternative electronic products due to their excellent energy density, rapid charge/discharge time, and safety. CuFe2O4-incorporated three-dimensional graphene sheet (3DGS) nanocomposites were studied by different characterization studies such as X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The electrochemical studies were based on cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. As prepared, 3DGS/CuFe2O4 nanocomposites exhibited an excellent surface area, high energy storage with appreciable durability, and excellent electrocatalysis properties. A supercapacitor with 3DGS/CuFe2O4-coated nickel foam (NF) electrodes exhibited an excellent specific capacitance of 488.98 Fg−1, a higher current density, as well as a higher power density. After charge–discharge cycles in a 2.0 M KOH aqueous electrolyte solution, the 3DGS/CuFe2O4/NF electrodes exhibited an outstanding cyclic stability of roughly 95% at 10 Ag−1, indicating that the prepared nanocomposites could have the potential for energy storage applications. Moreover, the 3DGS/CuFe2O4 electrode exhibited an excellent electrochemical detection of chloramphenicol with a detection limit of 0.5 µM, linear range of 5–400 µM, and electrode sensitivity of 3.7478 µA µM−1 cm−2.