Materials For Supercapacitors Research Articles

Wide electrochemical stability window of NaClO4 water-in-salt electrolyte elevates the supercapacitive performance of poly(3,4-ethylenedioxythiophene)

Water-in-salt electrolytes (WiSEs) have emerged as the primary preference in the domain of aqueous-based supercapacitors, thanks to their wide electrochemical stability window (ESW > 1.23 V). Here, we have chemically synthesized a unique lettuce coral-like structure of tosylate doped-poly(3,4-ethylenedioxythiophene) (PEDOT-tos) and tested it for supercapacitor application in a 17 molal (m) NaClO4 WiSE, achieving an ESW of 1.9 V. The energy and power densities (Ed and Pd) of our PEDOT-tos supercapacitor are as high as 14 Wh kg-1 and 7210 W kg-1, respectively, with over 80 % capacitance retention after 10,000 continuous Galvanostatic charge-discharge cycles. The NaClO4 WiSE increases the Ed and Pd of PEDOT by several folds compared to traditional H2SO4 electrolyte. This work encourages the exploration of a suitable combination of a PEDOT-based composite material and WiSE for high-performance supercapacitors.

Facile Biogenic synthesis of Europium doped lanthanum silicate nanoparticles as novel supercapacitor electrodes for efficient energy storage applications

In this work, we demonstrated for the first time, use of Europium doped lanthanum silicate nanoparticles (LS NPs) as electrodes for supercapacitor applications. Europium (Eu3+) doped (5 mol%) LS NPs were synthesized by green solution combustion method using Mexican mint leaf extracts. Various analytical techniques such as High-Resolution Transmission Electron Microscopy (HRTEM), Selected Area Diffraction (SAED), Powder X-ray Diffraction (PXRD), Fourier Transform Infra-Red Spectroscopy (FTIR) and Diffuse Reflectance Spectroscopy (DRS) techniques were used to confirm the morphological and structural characteristics of the synthesized nanoparticles. The HRTEM and SAED patterns confirms the formation of NPs having agglomerated structure with a particle size less than 50 nm. The PXRD patterns reveals crystalline cubic structure for the NPs. Further, the FT-IR spectra reveal the successful doping of Europium in Lanthanum Silicate NPs. The DRS (Diffuse Reflectance Spectroscopy) studies confirm the reduced band gap for Europium (Eu3+) doped (5 mol%) LS NPs. Cyclic voltametric and electrochemical impedance spectroscopy experiments were performed in an alkaline medium to compare the electrochemical activity of Eu3+ doped LS NPs with that of their undoped counterpart. The Eu3+ doped (5 %) LS NPs electrodes attained a specific capacitance of 373.3 Fg-1 at a current density of 0.5 Ag-1 in comparison to pure LS NPs which is about 267 Fg-1. The long-term stability of the Eu3+ doped (5 %) LS NPs electrodes show excellent stability up to 4000 cycles of operation in comparison pure LS NPs electrodes. Doping of Eu3+ had a favourable effect on the conductivity and electrochemical activity of LS NPs. Due to favourable green combustion synthesis, superior electrochemical performance, these Eu3+ doped LS NPs could be potential materials for new generation supercapacitors in energy storage applications.

Imine-based nickel/cobalt covalent organic framework with high rate and stability for supercapacitor

Abstract Due to their regular pore structure, long-range order, and structural stability, COFs (Covalent Organic Frameworks) have gradually been employed as electrode materials for supercapacitors. However, owing to their two-dimensional stacking structure, poor conductivity, and the lack of effective redox-active sites, they usually exhibit inferior rate performance and cycling stability. Therefore, we design an imine-based Ni0.7Co0.3-COF anchored with Ni/Co redox centres at the atomic level and adjust their proportion. This approach optimizes the electronic structure and enhances the electronic conductivity and redox activity of Ni0.7Co0.3-COF. Ni0.7Co0.3-COF are grown through thin-layered cross-linking, significantly shortening both the ion and electron transport pathways. This improves the contact area between electrolyte ions and electrode materials and enhances the utilization of redox centres, thereby substantially improving the rate performance (1300 F g−1 at 50 A g−1) and cycling stability (72% retention after 5000 cycles) of Ni0.7Co0.3-COF.

In-situ synthesis of synergistic ZnMn2O4/MnOOH nanocomposite as a cutting-edge pseudocapacitive electrode material for all-solid-state asymmetric supercapacitors

Currently, there has been a growing interest in constructing metal oxide composite structures through the in-situ synthesis method, especially for fabricating electrode materials for supercapacitors. This approach offers several advantages, such as improved contact between different materials, enhanced conductivity, efficient ion diffusion, and better overall electrochemical performance. This work investigates the synthesis of zinc manganese oxide and manganese oxyhydroxide (ZnMn2O4/MnOOH) composite using a solvothermal method. The structure, surface morphology, and composition of the ZnMn2O4/MnOOH composite were elucidated using standard physicochemical characterization techniques where the presence of ZnMn2O4 and MnOOH phases was confirmed and the ZnMn2O4/MnOOH nanocomposite behaved as a pseudocapacitive electrode with a notable specific capacitance of 1039.2 F g⁻1 at a current density of 1 A g⁻1. When subjected to a 10-fold increase in current density, the ZnMn2O4/MnOOH electrode maintained 50 % of its initial capacity, registering 513.4 F g⁻1. Additionally, the electrode showcased excellent cyclic stability, preserving 95 % of its initial capacity after 5000 cycles at 10 A g⁻1. Moreover, the constructed ZnMn2O4/MnOOH//activated carbon (AC) asymmetric supercapacitor (ASC) device attained a high energy density of 29.45 Wh kg⁻1 at a power density of 1384.5 W kg⁻1. The results confirm that the ZnMn2O4/MnOOH composite, prepared in a single synthesis step, shows great potential as a phenomenal pseudocapacitive electrode for energy storage applications.

Hydrothermally grown copper cobalt phosphate hydrate nanostars for supercapacitors: Investigation of their charge transfer kinetics

The transition bimetal phosphates are optimistic materials for supercapacitors. In this study, copper cobalt phosphate hydrate ((Cu0.35Co0.65)3(PO4)2·H2O) (CCPH) was deposited on Nickel foam using a hydrothermal method at different reaction temperatures as 120, 150, and 180 °C. X-ray diffraction analysis results in the monoclinic crystal structure of CCPH. The Raman study confirms the presence of the phosphate group. The scanning electron microscopy (SEM) study reveals that the reaction temperature-dependent morphological evolution takes place from nanostars to three dimensional (3D)-porous spongy balls-like structure. The elevating reaction temperature has changed the morphology from nanostars to 3D-porous spongy balls. The electrochemical analysis of the CCPH12 electrode resulted in a specific capacitance of 3390.73 mF/cm2 (518.02 µAh/cm2) at 10 mA/cm2 current density. The charge storage dynamics of the CCPH electrodes were analyzed using power law. The CCPH12 electrode delivered the energy density and power density as 0.142 mWh/cm2 and 2.75 mW/cm2, respectively.

Luffa vines-derived N, O doped porous carbon with high surface area for supercapacitors

Considerable attention has been devoted to creating porous carbons with exceptional surface area and porosity from biomass waste for energy storage devices. Herein, we employed a straightforward high-temperature carbonization and KOH activation method to synthesize nitrogen (N) and oxygen (O) co-doped porous activated carbons derived from luffa vines (LVACs). The impact of varying KOH concentrations on the morphology, structure, and electrochemical properties of LVACs was thoroughly investigated. The optimal mass ratio of KOH to LVACs at 1:6 achieved the maximum specific surface area of 3369 m2 g−1. At a current density of 1 A g−1, the LASC-6 electrode exhibits an impressive specific capacitance of 348.5 F g−1. It also demonstrates exceptional rate performance, retaining 70.6 % of its capacitance at a current density of 20 A g−1. The electrode possesses robust cycling stability, retaining 90 % of the initial capacitance after 5000 cycles. We assessed the practicality of LVAC-6 by constructing symmetric supercapacitors (SSCs) using KOH and [BMIM]BF4 electrolytes. The KOH and [BMIM]BF4 SSCs achieved specific capacitances of 86.75 and 50.31 F g−1, respectively, at a current density of 0.25 A g−1. Moreover, the [BMIM]BF4 SSC exhibited an impressive energy density of 51.05 Wh kg−1 at a power density of 346.15 W kg−1. Therefore, we propose a simple and cost-effective strategy to produce porous carbon materials with excellent electrochemical performance from discarded biomass waste, facilitating the preparation of environmentally friendly electrode materials for high-performance supercapacitors.

Probing the layer-dependent behavior of electronic properties and quantum capacitance in 2H MoS2: A computational analysis with emphasis on mechanical stability

The quest for clean, sustainable energy sources was prompted by the fast depletion of fossil fuels and the world's expanding energy requirements. To store renewable energy, it is important that effective energy storage devices such as supercapacitor (SCs) be manufactured. SCs offer a promising avenue for fast-charging, energy storage, and long-life cycles but maximizing their energy density remains a problem. This study theoretically explores the intrinsic Quantum capacitance (Cq) of MoS2 in the 2H phase with a few number of layers and how factors like electronic structure and density of states influence its capacitance behavior. In the present work, the first principles analysis utilizing computational modelling with Density Functional Theory (DFT) has been employed to investigate the Cq and surface charge density (σ) of MoS2. By explaining the connection between MoS2's electrical and structural properties with its Cq, valuable insights for optimizing it's SC performance were obtained. Both the density of states (DOS) and the Cq increase with the number of layers. Among the observed structures the highest value of Cq is observed for the three layered structure of 2H–MoS2 (2H3L-MoS2) at +1 V which is 1615.14 μF cm−2. Investigating the mechanical stability of optimized structure (2H3L-MoS2), a high Young's modulus of 180.46 GPa is observed for 2H3L structure. Hence, 2H-phase of MoS2 can be used as an excellent anode material for asymmetric SCs and flexible electronic devices.

Amorphous/polycrystalline NiMn selenide for high-performance supercapacitors.

Transition-metal selenides have been extensively studied as promising electrode materials for supercapacitors. Engineering amorphous/crystalline heterostructures is an effective strategy to improve rich active sites for accelerating redox reaction kinetics but still lacks exploration. In this study, an amorphous/crystalline heterostructure was designed and constructed by selenizing the self-sacrificial template NiMnS to generate amorphous Mn/polycrystalline Ni0.85Se-NiSe2 heterophase via the phase transformation from metal sulfide into metal selenide. The synergy of the complementary multi-components and amorphous/polycrystalline heterophase could enrich electron/ion-transport channels and expose abundant active sites, which accelerated electron/ion transfer and Faradaic reaction kinetics during charging/discharging. As expected, the optimal NiMnSe exhibited a high specific charge (1389.1 C g-1 at 1Ag-1), a good rate capability, and an excellent lifespan (88.9% retention). Moreover, the fabricated NiMnSe//activated carbon device achieved a long cycle life and energy density of 48.0Whkg-1 at 800Wkg-1, shedding light on the potential for use in practical applications, such as electrochemical energy-storage devices.

Unveiling the Hidden Potential of Two-Dimensional Black Phosphorus for Advanced Supercapacitor Applications.

In response to the contemporary energy crisis, researchers have intensified efforts to explore green and renewable energy sources alongside developing robust energy storage devices. Supercapacitors stand out among various storage options due to their high-power density and rapid charge-discharge cycles. However, their lower energy density poses a challenge, leading to exploration of diverse electrode materials, including black phosphorus (BP). BP, with its two-dimensional (2D) layered structure akin to graphene, exhibits exceptional properties, making it a promising candidate for various applications, including energy storage. This Perspective focuses on the properties of BP as an electrode material for supercapacitors, covering electrochemical performance, charge storage mechanisms, and synthesis methods. Challenges such as restacking and stability have prompted innovative strategies to enhance BP-based supercapacitors, both qualitatively and quantitatively. Furthermore, the fabrication of BP-based hybrid nanocomposites with carbonaceous polymers, conducting polymers, and other 2D materials is discussed, highlighting their efficacy as electrode materials along with future outlooks.

Controlled synthesis and electrochemical characterization of Co3V2O8 hexagonal sheets for energy storage applications

This work explores the hydrothermal synthesis of Co3V2O8 hexagonal sheets and their effects on the structure and electrochemical properties of the electrode material, with a focus on various urea concentrations. The prepared materials were extensively characterized through a variety of imaging and electrical techniques, such as asymmetric supercapacitor studies, cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) analysis, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). Morphological analyses revealed that distinct hexagonal sheets formed based on the urea content. XPS analysis has provided information about the oxidation states and chemical composition of the produced materials. The high capacitance of 293 F/g with an energy density of 14.68 Wh/kg at an applied current density of 1 mA/cm2 over CVO-0.6MU sample demonstrates the electrochemical capabilities of hexagonal sheets of Co3V2O8 as electrode materials for supercapacitor, as demonstrated by electrochemistry research such as GCD, CV, and EIS. Furthermore, we were able to attain a high capacitive retention of approximately 99 % columbic efficiency up to 20,000 cycles, as well as a high power density exceeding CVO-0.6MU, or 142 W/kg. These findings showed how highly feasible our as-synthesized CVO-0.6MU electrode material is as an energy storage device. The research carried out on asymmetric supercapacitor provides more evidence of the stable and promising capacitive performance of the synthetic materials, Additionally effect of the temperature on ASC were studied. This extensive work offers crucial details regarding the electrochemical characteristics and regulated manufacture of Co3V2O8 hexagonal sheets, which may find application in future cutting-edge energy storage technologies.

Nickel-Copper Bimetallic Oxide Nanoparticles Prepared by Simple Coprecipitation Method as High Performance Electrode Materials for Asymmetric Supercapacitors.

Supercapacitors with transition bimetallic oxides as pseudocapacitive materials have been of wide concern for their excellent energy storage performance. In this work, a simple coprecipitation method was used to synthesize the precursor, followed by calcination to prepare Ni-Cu bimetallic oxide materials. The structure, morphology and properties of the materials prepared by different precipitating agents and different calcination temperatures of NCO-H2C2O4 precursor were investigated. The optimum precipitant was determined to be H2C2O4, and Ni-Cu nanoparticles with regular lamellar microstructure were obtained at the calcination temperature of 400 °C. The nanostructure and morphology provide a large active channel for the rapid diffusion of electrolyte ions, and the specific capacitance of NCO-H2C2O4-400 electrode material can reach 740.31 F/g Cs at 1 A/g. The investigation of charge storage mechanism shows that the contribution rate of capacitance and diffusion control is about 37.9% and 67.2%, respectively. The electrochemical test results of the asymmetric supercapacitors (ASC) constructed with NCO-H2C2O4-400 and activated carbon show that the specific capacitance, energy density, and power density of the capacitor are 52.66 F/g, 16.45 Wh/kg, and 759.51 W/kg, respectively. Even after 5000 charge/discharge cycles at 5 A/g, it can still keep 90.57% of its initial capacity. This work not only provides competitive electrode materials for energy storage devices but also provides a feasible strategy for producing complex transition metal oxide materials with high capacitance performance.

Conducting Polymer-Based Gel Materials: Synthesis, Morphology, Thermal Properties, and Applications in Supercapacitors.

Despite the numerous ongoing research studies in the area of conducting polymer-based electrode materials for supercapacitors, the implementation has been inadequate for commercialization. Further understanding is required for the design and synthesis of suitable materials like conducting polymer-based gels as electrode materials for supercapacitor applications. Among the polymers, conductive polymer gels (CPGs) have generated great curiosity for their use as supercapacitors, owing to their attractive qualities like integrated 3D porous nanostructures, softness features, very good conductivity, greater pseudo capacitance, and environmental friendliness. In this review, we describe the current progress on the synthesis of CPGs for supercapacitor applications along with their morphological behaviors and thermal properties. We clearly explain the synthesis approaches and related phenomena, including electrochemical approaches for supercapacitors, especially their potential applications as supercapacitors based on these materials. Focus is also given to the recent advances of CPG-based electrodes for supercapacitors, and the electrochemical performances of CP-based promising composites with CNT, graphene oxides, and metal oxides is discussed. This review may provide an extensive reference for forthcoming insights into CPG-based supercapacitors for large-scale applications.

Synthesis and characterization of MoS2-COOH /Co composite as electrode material for Asymmetric supercapacitors (SCs) and devices

Transition Metal Dichalcogenide (TMD) supercapacitors have garnered significant interest due to their considerable potential. Contributing to the advancements in this field, our study focuses on the first successful synthesis of nanoparticle Co-doped MoS2-COOH using a hydrothermal approach. We examine its performance in electrochemical applications, specifically as an electrode for a supercapacitor. The MoS2-COOH/Co composite was characterized using various techniques, including X-Ray diffraction (XRD), Fourier-transform infrared spectrum (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, adsorption–desorption isotherm, and thermogravimetric analysis (TGA). The supercapacitive characteristics of MoS2-COOH/Co composite in a 1 M KCl electrolyte were analyzed through cyclic voltammetry (CV), continuous current charge-discharge cycling (CD), and electrochemical impedance spectroscopy (EIS). Following 3000 charge-discharge cycles, the MoS2-COOH/Co electrode, constructed on Ni foam, exhibited a unique capacitance of 2500 F g−1 with a cyclic retention of 85 % at a density of 20 mA cm−2. The synthesized material demonstrated excellent electrochemical performance for supercapacitor applications, as evidenced by Nyquist and Bode phase angle results.

Enhancing electrochemical performance of graphene oxide/polyaniline composite through plasma-assisted chemical cross-linking and surface modification

The composite of graphene oxide (GO) and polyaniline (PANI) is a promising electrode material for supercapacitors. A high loading of PANI can provide large specific capacitance, but it is a pervasive challenge to reconcile long-term cycling stability and high-rate discharge. Herein, we focus on a GO/PANI composite with low PANI content (∼25 wt%), developing a stable network of GO with an even distribution of PANI. Moreover, significantly enhanced electrochemical performance is achieved by utilizing plasma technology. The specific capacitance increases by 99 % to 433 F g−1 at 1.5 A g−1 after Argon (Ar) plasma treatment. Even at 15 A g−1, a capacitance retention rate of 91 % is obtained. After 15,000 cycles, the capacitance retention rate is 93 %, surpassing most previously reported GO/PANI composite electrodes. The further assembled all-solid-state supercapacitors can deliver a high energy density of 13.6 Wh kg−1 and exceptional cycling stability. According to results of characterization, it is demonstrated that Ar plasma imparts GO/PANI better surface morphology and achieves etching, reduction of GO, and cross-linking of GO and PANI, thereby activating the electrochemical activities of GO and PANI while ensuring stability. In this regard, the synergistic effects of cross-linking, reduction, and etching, and the mechanism are theoretically illustrated by dynamic differential equations. This work presents plasma processing unique charm for designing graphene-based materials via a customized strategy, exploiting an effectual approach to drive the applications of graphene-based materials in energy storage.

Comparative electrochemical properties of MO (ZrO2, V2O5) based polyaniline nanocomposites for high-performance supercapacitor applications

Due to its distinctive qualities, such as its moderate energy density, extended service life, rapid discharge–charge rates, and superior safety, supercapacitors (SCs) are gaining more and more attention. A zirconium oxide ZrO2 (Zr) and vanadium oxide V2O5 (VO) based PANI nanocomposites, denoted as (ZrP for ZrO2/PANI, and VOP for V2O5/PANI) are fabricated using hydrothermal technique in this research work. Morphological and phase investigations validated the random particle shapes with good crystallinity and purity of the samples. The N2 sorption/desorption isotherm reveals a mesoporous feature of the electrodes and the highest BET surface area (36.5 m2/g) with large electroactive sites, which offers abundant faradaic reactions for charge storage. The I-V characteristics confirm their excellent conduction capabilities as well. When utilized as electrodes for SCs in the three-electrode setup, the VOP composite electrode attains the highest capacitance of 1372 F g−1 at a scan rate of 5 mV s−1 compared with other active electrodes. Besides that, the VOP electrodes offer superior cyclic stability, with a retention rate of 94.28% even after 7000 consecutive charge/discharge cycles. It has been discovered that the in two electrode VOP asymmetric device exhibited remarkable specific capacitance of 651.36 Fg−1 at 5 mV s−1 demonstrating a significant capacitance retention of 87.6% over 6000 cycles. The results suggest that the material could be a good contender for electrode materials in supercapacitors.

Symmetric two-electodes pseudosupercapacitor from trichalcogenide MoS3-MoO3-poly-O-amino-benzenethiol nanocomposite

A novel nanocomposite, MoS3-MoO3/poly-O-amino-benzenethiol (MoS3-MoO3/POABT), has been synthesized in a one-pot process and demonstrates promising applications as a material for a two-electrode configuration supercapacitor. This nanocomposite exhibits remarkable morphological characteristics, featuring uniform particles with an average diameter of 80 nm and a porous structure. The advantageous morphology contributes to the enhanced performance of the fabricated pseudo supercapacitor. The evaluation of the charge/discharge behavior and cyclic voltammetry curves of the redox reaction of the MoS3-MoO3/POABT nanocomposite reveals its efficacy as a supercapacitor material. The specific capacitance (CS) achieved for this fabricated supercapacitor is noteworthy at 152 F/g. Furthermore, the energy density (E) peaks at 12.6 W h kg−1 when operating at a current density of 0.2 A/g. This high energy density demonstrates the supercapacitor’s ability to store significant energy for practical use efficiently. Importantly, its stability remains strong, with an impressive 98% retention after 250 cycles, and even after 1000 cycles, it only slightly decreases to 95%. This remarkable stability over extended cycling periods underscores the durability of the materials in the supercapacitor. Such reliable performance establishes the MoS3-MoO3/POABT nanocomposite as a dependable choice for supercapacitor applications, ensuring longevity and consistent performance in diverse energy storage needs.

Ultrasonic assisted synthesis of nanoporous carbon/CeVO4 nanocomposite for supercapacitor and photocatalytic applications

Here, nanoporous carbon (NPC)/CeVO4 nanocomposite synthesized via ultrasonic assisted method for supercapacitor and tartrazine dye degradation application. Transmission electron microscope (TEM) studies confirmed the CeVO4 nanoparticles well embedded on the NPC surface in the NPC/CeVO4 nanocomposite. Spherical shaped CeVO4 nanoparticles are well incorporated on the surface of NPC therefore NPC/CeVO4 nanocomposite which possess a porous-like structure would improve the supercapacitor applications and dye degradation performance. As expected, the specific capacitance (Cs) values (555 F g−1) of NPC/CeVO4 nanocomposite showed enhanced performance as compared to CeVO4 nanoparticles (234 F g−1) at a current density of 1 A g−1 and the capacitance retention of the designed electrode as 95 % after 5000 cycles. The photodegradation of tartrazine dye using pure CeVO4 nanoparticles and NPC/CeVO4 nanocomposite was explored under visible light irradiation. The photocatalytic degradation experiment demonstrated that the NPC/CeVO4 exhibits the maximum degradation efficiency (98.76 %) of the tartrazine with was reached within 120 min. Moreover, the rate constant of NPC/CeVO4 for tartrazine dyes decomposition was 0.0192 min−1 representing that it is two-fold higher than pure CeVO4 (0.0073 min−1). The superior electrochemical and photocatalytic properties of NPC/CeVO4 nanocomposite have been observed due to the well-designed structure and high surface area. Consequently, as-prepared NPC/CeVO4 material could be a promising material for electrochemical supercapacitor and dye degradation of the tartrazine organic pollutant.

Multifunctional applications of novel copper magnesium vanadate nanoparticles: Photocatalytic dye degradation and electrochemical properties

The multifunctional applications of nanomaterials in energy saving, electrochemical energy storage, and sensing devices are a current research trend. Novel Copper Magnesium Vanadate (CMV-CuMg2V2O8) nanoparticles have been synthesized by solution combustion method. The crystallite size calculated from XRD and TEM results was found to be 21 nm. The band gap estimated from UV–Vis DRS of CMV nanoparticles was found to be 3.82 eV. Its multifunctional applications were explored through for energy conversion, storage and sensing applications. Photocatalytic degradation of Acid Red-88 (AR-88) dye was conducted using CMV nanoparticles as photocatalyst under UV light. CMV nanoparticles modified carbon paste electrodes were prepared and its cyclic voltammetry (CV), Electrochemical impedence spectroscopy (EIS) and Galvanostatic charge–discharge (GCD) analysis were carried out using 1M KCl and NaOH electrolyte. With excellent specific capacitance of 266 Fg−1 in KCl electrolyte and 242 Fg−1 in NaOH electrolyte at 5 mV/s scan rate, CMV NPs was demonstrated to be a promising electrode material for supercapacitors. Electrochemical sensing analysis was carried out using the same electrode for the detection of paracetamol and ibuprofen within the range of 1–5 mM. The resulting copper magnesium vanadate nanoparticles have been verified as a possible electrode material for next-generation energy storage devices.

Oriented growth of NiCo metal–organic framework nanosheets on electrode materials for ternary mixed metal oxide supercapacitors

Metal–organic frameworks (MOFs) are porous structures that possess high specific surface areas, making them promising cathode materials for energy storage devices. However, solving the problems of random growth and easy aggregation of MOF nanosheets remains a challenge. In this study, hydrothermal and calcination methods were used to successfully create nickel cobalt molybdenum metal oxide (NCMO) nanoflowers, followed by the directional growth of NiCo–MOF on its surface. The oriented growth of NiCo–MOF nanosheets on NCMO nanospheres effectively prevented agglomeration, forming NCMO@NiCo–MOF with enhanced electrochemical sensitivity and a large quantity of active sites. When used as an electrode, NCMO@NiCo–MOF forms a large contact area with the electrolyte, demonstrating a high specific capacitance of 1724 F g−1 at a current density of 1 A g−1. Furthermore, at a power density of 824.8 W kg−1, an asymmetric supercapacitor constructed from NCMO@NiCo–MOF and activated carbon exhibited a high energy density of 44.5 Wh kg−1. This study presents a facile method for the assembly of MOF nanosheets for three-dimensional supercapacitors.

Natural N/O/S co-doped defect-rich functional carbon materials for aqueous supercapacitors: Effect mechanism of N-containing functional groups on chemical activation

The efficient synthesis of porous carbons with a micro-mesoporous composite structure from low-cost, multi-source biomass was of significant importance for the fabrication of carbon-based supercapacitors. A novel method for the preparation of micro-mesoporous composite carbon materials by co-pyrolysis of multi-source biomass coupled with KOH activation was proposed in this study. The N, O and S co-doped micro-mesoporous composite carbon materials were synthesized using the bamboo and spiral algae as the precursors and KOH as the activator. Spiral algae, as the main source of heteroatoms, played multiple roles (pore forming agent, dopant and enhancer) in the co-pyrolysis process. The enhanced effect of heteroatom doping on KOH activation facilitated the formation of microporous structures. The KCA-500–2 exhibited a porous structure dominated by micropores, with a specific surface area (SSA) of 2421.85 m2/g. At 0.5 A/g, KCA-500–2 displayed an excellent capacitance of 460F/g and outstanding rate performance (73.5 %). The assembled aqueous symmetric supercapacitor (KCA//KCA) demonstrated a maximum energy density of 19.09 Wh/kg at a power density of 150 W/kg. In addition, KCA//KCA attained 97.96 % capacitance retention after 9,000 cycles. This work revealed the synergistic mechanism between N-containing functional groups and KOH activation, suggesting a theoretical guidance for the synthesis of high-performance supercapacitors.