Supercapacitor Electrode Research Articles

A wearable cotton fiber-based supercapacitor electrode material with outstanding stability and photothermal performance utilizing AgNWs, NiCoAl-LDH, and PPy-NWs.

Designing cotton fiber (CF) based flexible electrode materials with both electrochemical energy storage and structural stability is crucial for the utilization of flexible supercapacitors in wearable devices. Nevertheless, the electrochemical properties of such materials are often constrained by suboptimal ion diffusion, a limited electroactive surface area, and inadequate structural integrity. Herein, Silver nanowires (AgNWs), NiCoAl hydrotalcite (NCA-LDH), and polypyrrole nanowires (PPy-NWs) are employed to construct a CF-based electrode material (PNHAS/CF) with high stability through a layer-by-layer self-assembly method. The PNHAS/CF with a high capacitance of 1207.58 mF cm-2 at 5mAcm-2 due to the faster electronic transmission paths of AgNWs and PPy-NWs, and the high specific capacitance of NCA-LDHs. The NCA-LDH stabilizes the PPy-NWs molecular chain, and the PPy-NWs winding structure can further enhance the PNHAS/CF's structural stability and prevent the AgNWs network from being destroyed, which guarantees the exceptional 87.5% capacitance retention after 2000cycles. The constructed symmetrical supercapacitor shows an energy density of 36.28 μWh cm-2 at 0.31mWcm-2 power density. The PNHAS/CF exhibits superb solar spectral absorptivity (~94.8%) and outstanding solar heating performance. Surprisingly, the fiber-based flexible electrode material and the assembled supercapacitor are expected to find applications in wearable intelligent electronics.

Coal-based Si self-doped disordered porous carbon for supercapacitor electrodes

In preparing activated carbon for coal-based supercapacitors, silicon in coal usually requires removal with hydrofluoric acid, which is neither economical nor environmentally friendly. However, silicon can be used as the anode in lithium batteries due to its high theoretical capacity. So silicon was retained to study its effect on supercapacitors. By retaining silicon without hydrofluoric acid treatment and activating at lower temperature, the prepared Si-doped activated carbon achieved a high specific capacitance of 318.3F/g at 0.5 A/g in the three-electrode test system. Omitting hydrofluoric acid treatment increased the specific capacitance by 49 %. Experimental results show that this 4.92 % silicon doping, mainly CSiO3, is the main reason for the enhancement. Density functional theory (DFT) simulations confirmed that CSiO3 improves double-layer capacitance by localizing surface charge and enhancing electrolyte ion adsorption, while also boosting quantum capacitance. High activation temperatures increase coal-activator reactions but also decrease disorder of the carbon, reducing specific capacitance. Temperature experiments show that the specific capacitance increases and then decreases in the range of 600 ∼ 950 °C, and reaches a peak at 650 °C. This study presents a simple, effective method to enhance supercapacitor performance with silicon-carbon precursors and provides detailed explanation on the capacitance enhancement mechanism for the first time.

Biogenic synthesis of porous CuO nanoparticles: Synergistic effects in photocatalytic dye degradation and electrochemical energy storage applications

This study explores the biogenic synthesis of CuO nanoparticles functionalized with Solanum nigrum, using Acalypha indica leaf extract as a reducing agent. The biogenically synthesized CuO nanoparticles were comprehensively characterized by various analytical techniques, involves X-ray diffraction analysis (XRD), BET surface area analysis (BET), energy-dispersive X-ray spectroscopy (EDAX), X-ray photoelectron spectroscopy (XPS), UV–Visible spectral analysis (UV), Fourier transform infrared spectroscopy (FTIR), fluorescence spectroscopy, photocatalytic degradation, antimicrobial assay, cytotoxicity assay, electrochemical analysis, and linear sweep voltammetry studies. The XRD analysis revealed end centered monoclinic phase with a 10 nm average crystalline size. BET analysis showed a mesoporous structure with a surface area of 11.54 m2/g. XPS and EDAX confirmed the presence of Cu2+ and O2− ions. SEM and TEM images indicated spherical, and porous nanostructures. UV–Visible spectroscopy identified an active optical range of 508–518 nm (2.40–2.45 eV), suggesting potential photocatalytic activity. The photocatalytic degradation efficiencies of Methylene blue (98.8 %) and Rhodamine B (95 %) were achieved after 100 min of irradiation. Antimicrobial tests demonstrated effectiveness against Staph. aureus, E. coli, Shigella flexneri, and Candida tropicalis. The nanoparticles exhibited notable cytotoxicity against colorectal cancer cells with IC50 values of 58.66 μg/ml and 66.78 μg/ml. Additionally, a symmetric supercapacitor electrode using these nanoparticles achieved a specific capacitance of 375 Fg−1 at the current density of 1 Ag−1. This research underscores the versatile applications of biogenic CuO nanoparticles in photocatalysis, antimicrobial treatments, cancer therapy, and energy storage.

Preparation of Cu‐MOF/Bi2WO6 Binary Composites by the Solvothermal Method: Its Characterization and Application as Supercapacitor Electrode Materials

ABSTRACTIn this research, the synthesis of a binary composite was conducted by combining Cu‐MOF and Bi2WO6. The resulting composite, denoted as CuBW, was systematically prepared with varying weight percentages: CuBW20, CuBW50, and CuBW80. To assess the properties of the composites, multiple characterization techniques were employed, including FTIR, XRD, FESEM‐Elemental Mapping, BET‐BJH, TEM, HRTEM‐SAED, and XPS. The composites were subjected to electrochemical testing utilizing a three‐electrode system, with 3 M KOH serving as the electrolyte. Through the electrochemical study, various parameters were evaluated and subsequently compared to determine any differences or similarities among the different compositions. CuBW80 exhibits superior performance with a specific capacity of 1137 F g−1, specific energy of 11 Wh kg−1, and specific power of 4000 W kg−1 at an operating current density of 0.5 A g−1. In the cyclic stability test, CuBW80 demonstrated superior performance by retaining approximately 83% of its initial specific capacitance over 10000 cycles. This further highlights its resilience and durability, reinforcing its suitability for extended and reliable use in energy storage applications.

Novel pseudocapacitive one-dimensional copper pyrophosphate (Cu2P2O7) nanofibers for asymmetric supercapacitor

The redox activity of a supercapacitor electrode can be significantly compromised by irregular, non-uniform, and agglomerated morphologies of the material. The preparation of a one-dimensional fibrous morphology not only ensures a consistent, continuous, and well-separated network of fibers but also results in an increased surface area compared to higher-dimensional structures. In this study, the fabrication of a continuous network of one-dimensional copper pyrophosphate (Cu2P2O7) nanofibers through a straightforward polymer-based electrospinning method followed by calcination at 900°C is reported. The resulting Cu2P2O7 monoclinic nanofibers exhibited an average diameter of 95 nm, highlighting the enhanced surface area of the material. By employing nickel foam (NF) as a current collector, the Cu2P2O7/NF electrode demonstrated a remarkable specific capacitance of 567.31 F g-1 (357.4 C g-1) at 2 A g-1 in 1 M LiOH electrolyte, surpassing performances in 1 M KOH and 1 M NaOH electrolytes. Furthermore, we designed an asymmetric supercapacitor (ASC) device configuration by incorporating carbon nanofibers (CNFs) as the negative electrode. Cu2P2O7//CNFs asymmetric supercapacitor showcases an exceptional specific capacitance, reaching 143.73 F g-1 (244.34 C g-1) at a current density of 0.4 A g-1. This remarkable performance is complemented by a notable energy density of 57.69 Wh kg-1 and power density of 1104.7 W kg-1. Furthermore, even at an elevated power density of 5132.25 W kg-1, the device maintained a considerable energy density of 22.81 Wh kg-1. These findings underscore the viability of Cu2P2O7 nanofibers as a compelling choice for energy storage devices.

Synthesis and electrochemical potentials of composite materials based on CrxV2−xO/S–g–C3N4 for supercapacitor electrodes

Synthesis and electrochemical potentials of composite materials based on CrxV2−xO/S–g–C3N4 for supercapacitor electrodes

Enhanced Electrochemical Performance of NiMn Layered Double Hydroxides/Graphene Oxide Composites Synthesized by One-Step Hydrothermal Method for Supercapacitors.

This study aims to enhance the performance of supercapacitors, focusing particularly on optimizing electrode materials. While pure NiMn layered double hydroxides (LDHs) exhibit excellent electrochemical properties, they have limitations in achieving high specific capacitance. Therefore, this paper successfully synthesized composite materials of NiMn LDHs with varying loadings of graphene oxide (GO) using a hydrothermal method. Systematic physicochemical characterization of the synthesized materials, such as powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), and Raman spectroscopy, revealed the influence of GO doping on the microstructure and electrochemical performance of NiMn LDHs. Electrochemical tests demonstrated that the NiMn LDHs/GO electrode material exhibited optimal electrochemical performance with a specific capacitance of 2096 F g-1 at 1 A g-1 current density and 1471 F g-1 at 10 A g-1, when GO doping level was 0.45 wt %. Furthermore, after 1000 cycles of stability testing, the material retained 53.3 % capacitance at 5 A g-1, indicating good cyclic stability. This study not only provides new directions for research on supercapacitor electrode materials but also offers new strategies for developing low-cost and efficient electrode materials.

Synthesis of Ni(OH)2‐g‐C3N4/C Composite by Biological Template for Asymmetric Supercapacitor

Nickel hydroxide (Ni(OH)2) is recognized as a promising material for electrodes in supercapacitors owing to its exceptional theoretical specific capacitance. However, Ni(OH)2 has several drawbacks, including a short cycle life, susceptibility to volume expansion, and poor electrical conductivity. In this work, Ni(OH)2 nanosheets anchored on layered g‐C3N4/C (Ni(OH)2–g–C3N4/C) are designed by biological template induction and a hydrothermal method. Ni(OH)2–g–C3N4/C has unique petal‐like structures, which can provide a vertical charge transport channel to increase reaction potential of the material during the charge–discharge process. The introduction of biomass carbon can solve the problem of the bulk phase accumulation of g‐C3N4 and can also improve the overall conductivity of the composite. Compared to Ni(OH)2 (522 F g−1), g‐C3N4/C (76.2 F g−1), and g‐C3N4 (16 F g−1), the Ni(OH)2–g–C3N4/C‐0.75 (NGC‐0.75) composite exhibits the highest specific capacitance of 1034 F g−1 at 1 A g−1. Furthermore, after 5000 cycles at 5 A g−1, the capacitance of the material is maintained at 85.97%. Meanwhile, the asymmetric supercapacitor based on the NGC‐0.75 shows a high energy density of 18.29 Wh kg−1 at the power density of 400.02 W kg−1 with excellent cyclic stability of 127.45% over 10 000 cycles.

Synthesis, fabrication, and performance evaluation of lanthanum doped nickel cobalt ferrite electrode for supercapacitors in energy storage applications

The escalating demand for high-quality energy storage devices has become a paramount concern in the contemporary scenario. Despite the potential of supercapacitors for high-quality energy storage, developing sustainable and improved electrode materials remains a challenge. This work investigates the synthesis and characterization of a novel optimally lanthanum-doped nickel cobalt ferrite, for its potential application in supercapacitors. The synthesized nano ferrite is utilized in a two-electrode system as a symmetrical supercapacitor device. The obtained morphological and electrochemical results of both two and three-electrode systems confirm their suitability for effective deployment in supercapacitor electrodes. A high specific capacitance of 706 F/g and energy density of 152.9 Wh/g is obtained for the fabricated device with a retention capacity of 86 % even after 10,000 cycles. The electrochemical results are also validated using an electrical method. The exploration of this lanthanum-doped nano ferrite is expected to be a suitable candidate for the fabrication of supercapacitor electrodes for augmented energy storage performance.

Pemanfaatan Limbah Ban Bekas untuk Sintesis Nanokomposit MnO2/C dengan Metode Hidrotermal sebagai Material Superkapasitor

Activated carbon from waste tires is used as MnO2 metal oxide doping in making MnO2/C-based nanocomposites into high-density and environmentally friendly supercapacitor electrodes. The MnO2/C nanocomposite synthesis process was carried out using the hydrothermal method by varying the mass of activated carbon by 1.25 g, 2.5 g and 3.75 g to determine the optimum results. Based on the results of research that has been carried out, it shows that MnO2/C can be used as a high density supercapacitor electrode. This is in accordance with the XRD test results which show that the MnO2 nanocomposite with the addition of C was successfully synthesized and has an orthorhombic crystalline phase. The SEM test results show that the material has almost the same morphology, namely many protrusions which make each particle have high roughness. The most optimal results were obtained from the MnO2/C-50 variation because it has the highest C element content, namely 39.93%, so it has the highest capacitance value of 5.791 f/g during the CV test. The GCD test shows that electrodes with a carbon variation of 2.5 g have a much longer and constant charge-discharge measurement time. In the EIS test, this variation shows a resistance value that is not too high and not too small, materials that have good storage capacity or capacity have moderate resistance.

Carbon bi-metallic molybdenum tungsten oxide composite as a potential electrode for high-performance asymmetric supercapacitor

Molybdenum tungsten oxide (MTO) bi-metallic structure was synthesized using Pechini method. Asymmetric supercapacitor (SC) was constructed using MTO/ active carbon (AC) and H2SO4 electrolyte. Different AC: MTO weight ratios proved a high impact on composite electrochemical performance. Galvanostatic charge-discharge tests demonstrated a capacitance of 336.75 F/g, with 37.11 % capacitance shrinking upon increasing the applied current to 5 A/g (50-fold) from 0.1 A/g. Such high-rate capabilities were attributed to lattice spacing induced by inserting tungsten (W) into the MO lattice. The optimized ratio of MTO/AC possesses a high specific energy and power of ∼120 Wh/kg and 256 kW/kg at 0.1 and 80 A/g, respectively. Moreover, the composite is showing ∼100 % retention values after 20k cycling at a high current of 80 A/g. Unlike many reports of using first-class transition metal oxides for energy storage devices, bi-heavy metal composite functionalization in SC applications is scarce. This potential composite between porous carbon and bi-heavy metal oxide suggested talented electrode materials for energy storage systems.

Fabrication of cerium vanadate-embedded on carbon based graphene material (rGO) with significant performance for supercapacitor electrode

This work examined the electrochemical properties of CeVO3 nanocomposite that were enhanced with reduced graphene oxide (rGO) and CeVO3 nanoparticles. The CeVO3/rGO fabricated using a typical hydrothermal process that was further characterized via XRD revealed the monoclinic crystalline structure of the CeVO3 nanoparticles. The presence of uniformly distributed particles structured CeVO3 and layer-structured (rGO) reduced graphene oxide in the nanocomposite materials was determined using scanning electron microscopy pictures. We evaluated the electro-chemical efficiency of the nanocrystals for enhanced working electrodes and supercapacitors with cerium vanadate (CeVO3) nanoparticles and the cerium vanadate (CeVO3) embedded on reduced graphene oxide (rGO). The analysis was conducted on 2.0 M aqueous KOH (potassium hydroxide) electrolytic solution and it achieved the capacitance of 355.46 F g−1 (10 mVs−1) was concluded by cyclic voltammetry analysis of the working electrode modified with pure CeVO3 nanomaterial. The addition of rGO improved the value of Cs to 947.30 F g−1 at the same scan speed (10 mVs−1). The CeVO3 nanoparticles and CeVO3/rGO nanocomposite exhibited the capacitance values of 698.54 F g−1 and 1403.35 F g−1 at 1 A g−1 respectively, as determined by GCD analysis. The fabricated with CeVO3 nanoparticles exhibited power density values of 254.1 W kg−1 and energy values of 25.05 W h kg−1. On the other hand, the CeVO3/rGO nanocomposite showed greater energy (Ed) and power (Pd) density of 54.72 W h kg−1 and 264.95 W kg−1, individually. After undergoing 5000th cycles, the material utilizing CeVO3/rGO composite maintained its stability. The electrochemical examination of the synthesized cerium vanadate nanoparticles revealed that the inclusion of rGO resulted in a hybrid capacitive nature and the proposed nanocomposite can be employed as supercapacitors or as electrodes in batteries as well as energy storage and generating device for future use.

Fabrication of asymmetric supercapacitors by laser processing of activated carbon-based electrodes produced from rice husk waste

The development of supercapacitors (SCs) by using carbon electrodes obtained from biomass waste simultaneously promotes the optimized use of the renewable energy by its high-powered storage, and the reduction of contamination in nature. Such industrial sector would be an excellent opportunity also for the developing nations, promoting their economic growth by the conversion of biowaste into added value goods. However, such carbon may not reach the desired performance for SCs. In this work, we used laser processing technology for enhancing the capacitance of SC electrodes composed of activated carbon obtained from rice husk produced in Nigerian farmlands. The activated carbon powder was synthesized by conventional carbonization-chemical activation processes and treated with microwaves. Afterwards, the CO2 laser processing of thin film electrodes composed of a mixture of the carbon powder with carbon black (conductive additive), and precursors as urea (for doping of the activated carbon with nitrogen), or manganese nitrate (for the crystallization of pseudocapacitive Mn3O4 nanoparticles on the carbon surface) was carried out for obtaining enhanced positrodes and negatrodes. The resulting hybrid electrodes exhibited a 3-fold increase of the capacitance (up to 134 F/g @ 10 mV/s) as compared to the raw carbon in the [0, 0.8] V potential window. Asymmetric SC devices integrated by carbon (-)//carbon-Mn3O4 (+) laser-treated electrodes, operating at 1.2 V voltage, revealed up to 300 × higher energy and power densities than symmetric SCs composed of raw carbon electrodes.

High-performance NF-loaded F-NiFe-LDH/rGO nanoflower/nanosheet composite electrode material achieving enhanced specific capacitance and energy density for supercapacitor

High-performance nanostructured F-NiFe-LDH/rGO composite electrode materials with F-NiFe-LDH nanoflowers and rGO nanosheets are synthesized in a controlled hydrothermal method by leveraging the strong synergistic effects between the components, enabling the construction of F-NiFe-LDH/rGO//AC asymmetric supercapacitors. The incorporation of rGO significantly enhances electron transport, resulting in an exceptional specific capacitance of 2860 F g−1 at a current density of 1 A g−1, with a remarkable capacity retention of 102 % after 1000 cycles. This represents a notable improvement in electrochemical energy storage, with surface-controlled capacitance contributing more in alkaline electrolytes for F-NiFe-LDH/rGO composite compared to F-NiFe-LDH alone. The asymmetric supercapacitor device exhibits a specific capacitance of 354 F g−1 at 1 A g−1, maintaining 92.31 % of its initial capacitance after 1000 charge/discharge cycles at 5 A g−1, and achieves an impressive energy density of 110 Wh kg−1 at 1 A g−1. The innovation of this work lies in the controllable preparation of nanostructured F-NiFe-LDH-rGO supercapacitor electrode material with enhanced specific capacitance and energy density by the synergistic effect between F-NiFe-LDH and rGO. This work offers a solid foundation for creating high-performance supercapacitor electrode materials and devices for energy storage applications.

Covalently linked 4-Aminopyridine on reduced graphene oxide for high performance electrochemical supercapacitor electrode material

The portability of electrical devices requires the demanding but essential task of improving supercapacitor energy density while preserving stability. Introducing an amine heterocyclic compound on a reduced graphene oxide (rGO) layer can enhance its capacity for energy storage. Here, we employed Catharanthus roseus flower extract as a green reducing agent to prepare rGO for the first time. A stable covalently linked 4-AP-rGO was produced through combining of 4-Aminopyridine on the rGO layer via nucleophilic substitution reaction process. The synthesized materials were systematically characterized by FT-IR, UV–visible, Raman, powder XRD, XPS, SEM, and TEM. Furthermore, the screen-printed carbon electrode (SPCE) was modified with 4AP-rGO (4AP-rGO/SPCE) to evaluate the electrochemical properties using CV, GCD, and EIS in 1 M H2SO4. The electrochemical performance of the 4AP-rGO/SPCE modified electrode was compared with unfunctionalized rGO. The pseudocapacitive efficacy of the 4AP-rGO was exceptional as evidenced by its high energy density (12.27 × 10−4 Wh kg−1), high power density (350.6 × 10−3 W kg−1), and high specific capacitance of (180.3 × 10−3 F g−1) at 1 A g-1. Over 10,000 cycles at 1 A g-1, it maintained 98.8 % capacitance, exhibiting exceptional cycling stability. The energy density of 4-AP-rGO is 2.1 times higher than that of rGO, indicating that it is a suitable candidate for energy storage applications.

Uniform carbon pillars array grown on boron doped diamond for high-performance supercapacitors and hydrogen evolution reactions

Carbon materials have marvelous ability in energy storage and microelectronics as a result of the high specific surface area and electrical conductivity. However, the low stability and the low power density caused by low potential window make it particularly difficult for their application in aqueous electrolysis. In this study, boron doped diamond (BDD) with wide potential window is used as substrate and Ni as catalyst to grow uniform carbon pillars (CP) by microwave plasma chemical vapor deposition method. The composite structure (CP/BDD) yields significant specific capacity (91.64 mF cm−2 at 0.1 mA cm−2) and cycling stability (92.3 % retention rate after 20,000 cycles) when used as the electrode of supercapacitors, superior to most of BDD-based electrodes. The prepared symmetrical supercapacitor devices maintain their excellent electrochemical performance characteristics (power density of 4.4 mW cm−2 and energy density of 13.4 μW h cm−2), as well as high cycling stability. In addition, the electrode has considerable application potential in electrochemical hydrogen production with low hydrogen evolution potential and small Tafel slope value. These results illustrate the potential of BDD based composites for using as energy storage electrodes for electronic products and energy conversion equipment.

Unraveling quantum capacitance of black phosphorene by the doping of non-metals for energy storage applications using DFT method

Supercapacitor plays a pivotal role as energy storage devices in the context of eliminating energy resources. Black Phosphorene (BP) is highly regarded as a potential electrode for supercapacitor (SC) because of its outstanding properties, including excellent carrier mobility and unique electronic properties. In this research work, the monolayer of BP and bilayer of BP (BP/BP) structure is investigated by using DFT. Moreover, the effect of doping and co-doping of non-metal (oxygen, nitrogen) in the mono- and bi-layer was also investigated to increase their performance by modulating the charge storage, and electronic properties of BP. The structural properties, density of states, quantum capacitance, surface charge density, bader charge analysis, isosurface charge density difference, integrated charge density of monolayer and bilayer are studied. The density functional theory (DFT) is used to calculate all above mention properties. DFT-D3 method with Becke-Johnson damping function is used as dispersion correction factor for all the calculations of bilayer. The calculated results find that bilayer structure gives better results as compared to monolayer structure. In this work, results also revealed that doping of oxygen and nitrogen atom significantly enhance the CQ and Q of mono- and bi-layer structure. For aqueous system, all the composites exhibited asymmetrical behavior except BP/BP bilayer. BP-N/BP-N (1369.8µC/cm2), and BP-O/BP-O (-1298.1µC/cm2) bilayer structure are best for anode and cathode material. In case of ionic/organic system, all composites showed asymmetrical behavior. BP-O/BP-O (-6053.5µC/cm2), and BP-N/BP-N (9329.8µC/cm2) bilayer structure is best cathode and anode material.

Harnessing dysprosium telluride/GPE as an effective electrode for energy storage and conversion

Hydrogen stands out as a clean alternative to fossil fuels, and its production via water electrolysis is promising, although the slow kinetics of the oxygen evolution reaction (OER) pose a significant challenge. Alongside energy conversion, the quest for effective energy storage remains critical. This study explores the potential of dysprosium telluride (Dy2Te3) as a highly efficient catalyst for OER and a supercapacitor electrode. The hydrothermally synthesized Dy2Te3 exhibits exceptional OER activity, characterized by an overpotential of 294 mV at 1.48 V vs. RHE, a low Tafel slope of 48 mV dec−1, and minimal interfacial resistance of 13 Ω. In a 1.0 M KOH solution, Dy2Te3 nanoparticles demonstrate outstanding supercapacitor performance, achieving a power density of 283.5 W kg−1, specific capacitance of 645.33 F g−1, and energy density of 22.8 Wh kg−1 at 1 A g−1. The high performance is attributed to enhanced electrical conductivity and a low impedance of 0.352 Ω in a three-electrode system. In a practical two-electrode configuration, Dy2Te3 nanoparticles deliver a specific capacitance of 479 F g−1, energy density of 94 Wh kg−1, and power density of 0.32 kW kg−1, with a reduced interfacial resistance of 1.03 Ω. These results underscore the potential of Dy2Te3 as a viable electrode material for both supercapacitors and water splitting, offering valuable insights into the application of lanthanide-based metal chalcogenides in energy technologies.

Pillar-Supported 2D Layered MOFs with Abundant Active-Site Distributions for High-Performance Alkaline Supercapacitors.

The development of two-dimensional (2D) layered metal-organic frameworks (MOFs) through precise molecular-level design and synthesis has emerged as a prominent research endeavor. However, the utilization of MOFs in their pristine form as electrodes for supercapacitors poses a significant challenge due to their limited tolerance in alkaline environments. To address these issues, we have developed Co- and Cu-based pillar-layered MOFs by regulating the structure of their inner layers through introducing an alkaline N-containing "pillar" to enhance the performance of alkaline supercapacitor electrodes. From the microstructure study and theoretical calculation, the high-density redox centers and efficient chemical bonding modes of Co-MOF determine a unique electron conduction pathway, resulting in excellent energy storage performance. This study underscores the significance of chemical bonding modes and active-site distribution in enhancing the energy storage capabilities of pillar-layered MOFs in alkaline environments, presenting a promising approach for the development of high-performance MOF-based materials for supercapacitor applications.

Unlocking hierarchical hollow nanoblocks of NiMo sulfide with extended interlayer spacing of Mo-S units for high-performance supercapacitor

Molybdenum sulfide (MoS2) has been investigated as electrode of supercapacitor due to its unique structure. However, the restricted availability of active sites and sluggish behavior at the basal surface impede its improvement. Here we propose an unlocking hierarchical hollow strategy to synthesis the bimetallic sulfide heterostructures loaded on the ultrathin carbon (NiS/MoS2@UC). The unlocking hierarchical hollow structure and extended S-Mo layer provide interconnected channels for rapid electrolyte ion transport, while the heterojunction interface promotes the electron transfer and redox reaction. As a result, NiS/MoS2@UC − 2 exhibits a high specific capacitance of 616.7F g−1 at the current density of 1 A/g, which is approximately 10 times higher than that of MoS2@UC and 6 times higher than that of NiS@UC. Moreover, NiS/MoS2@UC − 2 demonstrates a high energy density of 7.7 Wh kg−1 at the power density of 300 W kg−1 with excellent cycling durability.