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Activated carbon has potential in energy storage and conversion, however, conventional methods often struggle to enhance specific surface area and control pore structure precisely, hindering its application in hydrogen storage and electrochemical fields. Therefore, this study aims to utilize pine sawdust as carbon precursor and employ "restricted activation" technology to regulate the specific surface area and pore structure of carbon materials, thereby enhancing their performance in hydrogen and electrochemical energy storage. Results demonstrate activated carbon's exceptional microporous structure and specific surface area, leading to outstanding hydrogen storage (achieving a capacity of 7.73 wt% at 77 K and 40 bar) and electrochemical properties (with the highest energy density of 12.92 Wh∙kg−1 and power density of 125 W kg−1). A comprehensive array of contrasting results has revealed that while micropores experience single-layer adsorption, the engagement of certain micropores and small mesopores in the physical adsorption process markedly boosts hydrogen storage capacity. This investigation sheds light on the relationship between material structure and storage performance, offering insights into multifunction carbon materials for high-capacity hydrogen storage and superior electrochemical performance. • Enhanced sample surface area by physical-chemical dual activation methods. • Waste gas recycling to achieve double reuse and protect the environment. • Porous carbon materials offer excellent hydrogen storage and supercapacitor. • The conversion treatment can also be applicable to other areas of biomass activation. [ABSTRACT FROM AUTHOR]

This investigation is motivated by the surge of interest in materials, combining high spontaneous magnetization and pseudocapacitance at room temperature. Ferrimagnetic MnFe 2 O 4 offers benefits of high magnetization. However, the non-pseudocapacitive behavior, low capacitance and high resistance of MnFe 2 O 4 are limiting factors for its applications in magnetic pseudocapacitive devices. This investigation demonstrates that nearly ideal pseudocapacitive behavior can be achieved for MnFe 2 O 4 electrodes in Na 2 SO 4 electrolyte. High pseudocapacitance is observed in positive and negative potential ranges and two different charging mechanisms are proposed. High capacitance is achieved at a low impedance. The ability to achieve comparable and high areal capacitances in the positive and negative potential ranges facilitates the fabrication of a symmetric pseudocapacitive device, containing ferrimagnetic MnFe 2 O 4 as cathode and anode material for operation in enlarged voltage window of 1.6 V. The symmetric device shows capacitance of 0.92 F cm−2 at a current density of 3 mA cm−2. The individual electrodes and device show good cycling stability. The approach is based on the use of murexide and gallocyanine as redox-active dispersants and charge transfer mediators. The analysis of testing results provides an insight into the influence of chemical structure, charge and redox properties of the dispersants on the capacitive behavior. The ability to fabricate a pseudocapacitive device, containing two ferrimagnetic electrodes is promising for energy storage, water purification and novel applications based on magnetocapacitive effects. [ABSTRACT FROM AUTHOR]

Renewable energy sources, such as wind, tide, solar cells, etc, are the primary research areas that deliver enormous amounts of energy for our daily usage and minimize the dependency upon fossil fuel. Paralley, harnessing ambient energy from our surroundings must be prioritized for small powered systems. Nanogenerators, which use waste energy to generate electricity, are based on such concepts. We refer to these nanogenerators as energy harvesters. The purpose of energy harvesters is not to outcompete traditional renewable energy sources. It aims to reduce reliance on primary energy sources and enhance decentralized energy production. Energy storage is another area that needs to be explored for quickly storing the generated energy. Supercapacitor is a familiar device with a unique quick charging and discharging feature. Encouraging advancements in energy storage and harvesting technologies directly supports the efficient and comprehensive use of sustainable energy. Yet, self-optimization from independent energy harvesting and storage devices is challenging to overcome. It includes instability, insufficient energy output, and reliance on an external power source, preventing their direct application and future development. Coincidentally, integrating energy harvesters and storage devices can address these challenges, which demand their inherent action. This review intends to offer a complete overview of supercapacitor-based integrated energy harvester and storage systems and identify opportunities and directions for future research in this subject. [ABSTRACT FROM AUTHOR]

A symmetric supercapacitor device with high electrochemical performance was assembled using the TC- P -3 hybrid film electrode. [Display omitted] Robust, conductive and flexible electrode materials have been the focus of attention in portable, wearable electronics. However, it is still a significant challenge to achieve synergistic development of multiple properties simultaneously. Herein, we propose a combination of microscale design and nanostructures strategy to prepare MXene/cellulose nanofiber-poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate (Ti 3 C 2 T x /CNF-PEDOT:PSS, TC-P) hybrid film by a simple in-situ polymerization and vacuum filtration process. CNF serves as the supporting skeleton of PEDOT:PSS, effectively mitigating its self-aggregation and structural deformation due to the expansion/contraction of the polymer network. And the CNF-PEDOT:PSS composite is capable to open up the interlayer space of Ti 3 C 2 T x , which reduces the self-stacking of Ti 3 C 2 T x nanosheets. The strong interactions among the three components enable the hybrid film electrode to possess both flexibility and high electrochemical properties. As a result, the film electrode exhibits a remarkable tensile strength of 77.4 MPa and an excellent conductivity of 162.5 S cm−1, as well as an outstanding areal specific capacitance of 896 mF cm−2 at 4 mA cm−2. Moreover, the assembled symmetric supercapacitor (SSC) device displays a large areal energy density of 62 µWh cm−2 at a power density of 800 µW cm−2 and demonstrates a long cycle life with 85.1 % capacitance retention after 10,000 GCD cycles. This study provides an effective strategy to balance mechanical flexibility and electrochemical properties, providing an inspiration to prepare flexible electrodes that are widely applied in a new generation of portable, wearable electronics. [ABSTRACT FROM AUTHOR]

The current application of gel electrolytes in energy storage fails to meet the demand for higher ion transport and excellent mechanical properties due to the low ionic conductivity and poor mechanical properties. Herein, a novel strategy is proposed to graft oligomer polyetheramine on the surface of MXene to achieve a transformation from solid MXene to MXene nanofluid avoiding oxidation and aggregation of MXene, and then it is introduced to gel electrolytes providing ion transport channels and mechanical properties. The synergistic effect on the core of MXene and the canopy of polyetheramine produce Lewis acid–base interactions on electrolyte ions, which not only promote electrolyte dissociation but also provides ion transport path‐way. The experiment and molecular dynamics simulations show that the ionic diffusion ability of electrolyte ions is enhanced, because the MXene and polyetheramine promote electrolyte dissociation and reduce the electrostatic interference between anions and cations. The specific capacity of the assembled supercapacitor is 114.28 F g−1 at 1 A g−1 current density, and the capacity retention rate is 91.30% after 3000 cycles. This work provides a new insight for fabricating high‐performance devices. [ABSTRACT FROM AUTHOR]

Metal-organic framework (MOF) derived metal oxide nanostructures hold immense promise as electrodes for energy storage/conversion applications, notably in supercapacitors and urea oxidation. This study explores into optimizing such nanostructures, specifically focusing on a Zr/Ni ratio of 1:1, which has exhibited favorable electrochemical and catalytic performance. Employing thorough characterization methods, including PXRD analysis, we verified the successful synthesis of a ZrO 2 /NiO binary phase (i.e. Zr/Ni) nanostructure via the MOF-derived approach, showcasing its versatility as a catalyst across diverse energy conversion domains. The Zr/Ni nanostructure electrode displayed noteworthy characteristics, boasting a capacity of 432 C/g alongside exceptional cycling stability of 99%, reflecting battery-like electrochemical behavior. Furthermore, in an asymmetric device setup (Zr/Ni//AC), it achieved a notable potential of up to 1.4 V with an impressive power density of 1044.56 W/kg. Additionally, the Zr/Ni nanostructure demonstrated efficient electrocatalytic activity in urea oxidation, evidenced by a maximum current density of 60 mA/cm2. This underscores its viability as a preferred catalyst in energy conversion applications, signaling opportunities for further exploration and advancement in this dynamic field. [Display omitted] • Successful formation of a binary phase of Zr/Ni nanostructure achieved by single step route. • Zr/Ni nanostructure demonstrated a specific capacity of 432C/g. • Zr/Ni//AC device showed ED of 4.08 Wk/g@ 420 W/kg. • Zr/Ni nanostructure exhibits a low onset voltage (1.34 V) in urea oxidation. • Zr/Ni nanostructure shows the highest current density of 60 mA/cm2. [ABSTRACT FROM AUTHOR]

The recognition of the importance of nanostructures is mainly due to the development of nanotechnology. For further developments in materials sciences, a concept that integrates nanotechnology with material chemistry to fabricate functional materials has to be proposed. Nanoarchitectonics will carry out this task. In nanoarchitectonics, we architect functional material systems from nano-units (atoms, molecules, nanomaterials). The methodology is not specific to any particular material or application. It covers a wide range. Therefore, nanoarchitectonics can be thought of as the method for everything in materials science. As typical demonstrations for usages of nanoarchitectonics, this review paper presents our work on nanoarchitectonics for supercapacitors. We divide it into two categories with different approaches. The first is the development of carbon materials as supercapacitor electrode materials from biomass. The second category is preparing carbon materials using structures created by supramolecular assembly of fullerenes such as C60 and C70. By presenting examples using opposite starting materials, a complex natural material, and an ultimately simple molecule, we will demonstrate the versatility and breadth of possibilities of this approach. [ABSTRACT FROM AUTHOR]

Over the last decade, there has been vital increase in utilization the renewable energy sources, leading to a heightened need for the production of a highly effective energy storage system. Enhancing the characteristics of the electrode material has the potential to address such issues. The perovskite composite comprising corban-based materials has many applications, primarily in energy storage system. In this manuscript, hydrothermal method was performed to synthesized a nanocomposite material consisting of perovskite like BaSnO 3 & reduced graphene oxide (rGO) for purpose energy storage application. This work used physical and electrochemical techniques to examine the properties of the synthesized BaSnO 3 /rGO nanocomposite material. The presence of rGO in BaSnO 3 /rGO nanocomposite resulted in an enhanced surface area because of its heightened redox activity. The BaSnO 3 /rGO nanocomposite sample demonstrated an electrochemical characterization through capacitance (C s) value of 1264 F g−1 @ 1 A g−1 with power 255W kg−1 and energy density of 45 Wh kg−1. Moreover, the material exhibited the highest level of cyclic stability after undergoing 5000th cycles and also stable for 50 h. Furthermore, the enhanced electrochemical characteristics of the synthesized BaSnO 3 /rGO nanocomposite may be ascribed to larger surface area, reduced resistances and accelerated flow of electrolytic ions in comparison to the separate components. However, the BaSnO 3 /rGO nanocomposite has promising potential as fabricated electrode sample for various electrochemical applications and future storage device electrodes. [Display omitted] • The BaSnO 3 /rGO nanocomposite electrode was synthesized for supercapacitor electrode. • The martial showed specific capacitance of 1264 F g−1 at current density of 1 A g−1. • The material demonstrated energy density for 45 Wh kg−1 and power density for 255 W kg−1 • The nanocomposite exhibited solution resistance 3.21 Ω. • The BaSnO 3 /rGO nanocomposite displayed enhanced capacitive behaviour. [ABSTRACT FROM AUTHOR]

The alarming rise of pathogen antibiotic resistance presents a major global health challenge and demands a novel way to control the microbial infections. Simultaneously, nanotechnology has found numerous uses in electrical as well as electronic systems, including timing, filtering, power factor adaptation, and capacitors for energy storage. This work investigates the synthesis and characterization of a silver nanoparticle (AgNPs) utilizing Calotropis procera (CPL) leaf extract. The optimization of synthesis process and the reduction of nanoparticles (NPs) were validated by UV–visible spectroscopy. AgNPs' was exhaustively characterized for morphology, crystallinity, zeta-potential, and structural properties. The produced NPs demonstrated a wide range of characteristics, such as antioxidant, antidiabetic, antibacterial, and antifungal effects. Furthermore, remarkable electrochemical performance was indicated by the CPL-AgNPs electrode, which has mesoporous, clustered sphere-shaped particles onto a flexible stainless-steel substrate. This highlights the electrode's potential in energy storage applications. Copper monosulfide served as the anode and CPL-AgNPs as the cathode electrode in tested hybrid supercapacitor devices, which proved remarkable specific capacitances, high specific energy, and exceptionally high specific power. In order to address the twin challenges of antimicrobial resistance alongside advanced energy storage, this study provides a novel and thorough analysis of the basic electrochemistry as well biological properties of AgNPs, clarifying their potential storage of charges mechanisms and biomedical applications. Highlights: CPL-AgNPs exhibited improved biomimetic attributes. Antibiotic resistance against pathogens were challenged through use of CPL-AgNPs. Supercapacitor application of facile synthesized AgNPs for the first time demonstrated improved physical application. [ABSTRACT FROM AUTHOR]

Owing to their characteristics like fast charge–discharge rate, very long life, simple geometry and eco-friendly nature, supercapacitor is an emerging technology to fulfil the present and future requirements of the energy. The performance of a supercapacitor is derived from the composition and morphology of the electrode. 2D materials possess various excellent structural properties like surface area, flexibility in the atomic scale dimension and mechanical strength with high electrical conductivity. This makes them an entrusted material to be used as an electrode material. The teaming of 2D materials and layered transition metal dichalcogenides have been of great interest for electrode materials. In this study, the reduction of graphene oxide is done by an environment-friendly synthesis method using cow urine, and then, synthesizing the reduced graphene oxide (rGO) and transition metal dichalcogenides (TMD) composite using the refluxing method. The modified pencil graphite electrode (PGE) was functionalized using the above composite and the performance is comparable to that of glassy carbon electrode. Our main motive was to develop a low-cost, sustainable and highly effective MoS2–rGO/PGE, which is completely based on an environment and eco-friendly method using natural precursors. The prepared MoS2–rGO nanocomposite was characterized by XRD, SEM and EDX, which revealed the formation as well as its morphological scenario. MoS2–rGO/PGE is explored as electrode material by electrochemical characterization with the 3-electrode system through cyclic voltammetry and electrochemical impedance spectroscopy, which exhibit maximum specific capacitance with good cycle stability. [ABSTRACT FROM AUTHOR]

In this study, the polygonal structure of WO3 nanoparticles was constructed by the hydrothermal route, and the prepared materials were utilized for supercapacitor applications. The synthetic materials are WO3 nanoparticles in their monoclinic phase, according to the X-ray diffraction data. The morphologies of the WO3 samples are polygonal like and scanning electron microscope and transmission electron microscopy have confirmed it. To investigate the supercapacitance behavior of polygonal WO3, various techniques were used, such as galvanostatic charge–discharge, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The polygonal WO3 nanoparticle modified on Ni-foam as a working electrode has a specific capacitance value of 870 F g−1 at 0.25 A g−1. The polygonal structure of WO3 nanoparticle-coated Ni-foam electrodes was very stable compared to other fabricated electrodes over the 10,000 cycles. The fabricated polygonal structure of the WO3 electrode has high capacitance retention (100.2%) and high coulombic efficiency (99%). The polygonal structure of WO3 makes it a particularly effective electrode material and a substantially better candidate for energy storage, especially supercapacitors. [ABSTRACT FROM AUTHOR]

This paper presents a novel binder-free electrochemical synthesis of a porous ternary composite comprising polyaniline/multiwall carbon nanotubes decorated with silver nanoparticles (Ag@PANI/MWCNTs), which serves dual functions as a photocatalyst for methylene blue degradation and as an electrode for high-performance supercapacitors application. Various characterization techniques confirm that the synthesized Ag@PANI/MWCNTs composite exhibits excellent optical, chemical, electrical, structural, morphological, electrochemical and photocatalytic characteristics. The composite exhibits excellent electrochemical and photocatalytic efficacy attributed to its porosity, higher surface area, conductivity and rapid redox properties. Electrochemical tests reveal specific capacitance of 862 F/g, energy density of 65.78 Whkg−1, power density of 444.44 Wkg−1 and cycling stability with 79% capacitance retention even after 10,000 cycles. As a photocatalyst, the composite achieves approximately 95% degradation in 25 min with reusability up to five cycles. It also exhibits high transient photocurrent responses (0.36 mA/cm2) and a high-rate constant (0.13 min−1), confirming excellent photocatalytic activity. The synergistic effect of PANI/MWCNTs and the incorporation of Ag nanoparticles contribute to the outstanding performance of the synthesized nanocomposite. Thus, it is expected that the synthesized Ag@PANI/MWCNT is a promising ternary composite which may prove to be a noble material for photocatalytic and energy storage-related devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors. [ABSTRACT FROM AUTHOR]

In the present work, α-MnO2 thin films are deposited on a stainless steel substrate using the hydrothermal method by varying hydrothermal temperature. The impact of different hydrothermal temperatures on the structural, morphological and electrochemical performance of prepared thin films is investigated. The XRD studies confirm the tetragonal crystal structure of prepared MnO2 thin films. The electrochemical behaviour was studied using three-electrode system in 1 M KOH electrolyte. The high electrochemical performance with a maximum specific capacitance of 442 F g−1 at a scan rate 5 mV s−1 and energy density of 62 Wh kg−1 at a power density of 5.2 kW kg−1 has been obtained. The specific capacitance shows 90% capacitance retention after 2000 GCD cycles. [ABSTRACT FROM AUTHOR]

Among various nano-forms, carbon being explored as electrode materials for supercapacitor, carbon aerogels (CA) manifest several excellent features owing to their 3D interconnected mesoporous structure, high surface area and good electrical conductivity. With an objective for further enhancement of its efficacy, CA doped with nitrogen was synthesized using solvo-thermal gelation of resorcinol, melamine and furfuraldehyde in isopropyl alcohol medium at 130°C and ~20 bar. Based on the earlier detailed investigation, ~10.6 at.% of nitrogen-doped CA (N–CA) that exhibits the highest specific surface area and mesopore surface area was used for the fabrication of supercapacitor. Further, synergetic effect of the improved wettability due to inclusion of heterogeneous species, increased conductivity due to incorporation of graphitic nitrogen and high content of pseudocapacitive pyridinic as well as pyrrolic nitrogen in the carbon network, resulted high specific capacitance of ~218 F g−1. The N–CA-based supercapacitor (SC) module was fabricated with 18S-2P cell configuration with cell capacitance of ~450 F. Using international testing standards IEC/EN 62391, overall capacitance of ~61.8 F at 12.5 V operation containing total energy storage of ~4.5 kJ with low equivalent series resistance (ESR) of ~5.5 mΩ was achieved for the fabricated SC module. These parameters are comparable to the similar module of Maxwell Inc. The module has been demonstrated for cranking a car engine of 998 cc and a current of ~208 A was drawn at the time of ignition. [ABSTRACT FROM AUTHOR]

Lignin is a nature's wonder most abundant aromatic biopolymer and a promising precursor for a wide range of sustainable carbon materials (CMs). However, the effects of lignin structural heterogeneity on the properties and performance of lignin-based CMs are still poorly understood. In this paper, we address the influence of the lignin structural heterogeneity on the properties of lignin-based activated carbons (ACs). Taking two structurally different kraft (KL) and hydrolysis (HL) lignins, we show that they result into ACs with different properties and electrochemical performance in supercapacitor application. In similar carbonization and activation conditions, ACs from HL showed higher specific capacitances than ACs from KL. The difference between the two groups of ACs could not be solely attributed to the difference in their specific surface areas. They were rather found to result from different particle morphologies, pore size distributions, pore wall nanostructures, and surface chemistries, as revealed by multivariate data analyses. Moreover, we observed that KL and HL had different thermophysical behaviors and reactivities during the thermal treatment, which would have influenced the porosity development and surface oxygenation levels and consequently the electrochemical performance of the derived ACs. This work also shows that it is possible to engineer ACs from HL with electrochemical performance close to the commercial YP-50F Kuraray AC, which implies that less pure, carbohydrate-containing lignins are no less advantaged compared to purer KL to produce high-performance ACs for supercapacitor application. [ABSTRACT FROM AUTHOR]

The porous 3D structure of zinc-doped carbon aerogel is created from cellulose precursor extracted from banana stem—a biomass waste that is abundant in Vietnam—through a simple and easy-to-implement 2-step process. Additionally, sodium alginate was used as a crosslinker and zinc acetate as a network coupling agent that can strengthen the gel system and increase the porosity of the carbon aerogel. In addition, zinc acetate also acts as a doping agent, increasing the ionic mobility of the material. Zinc-doped carbon aerogels synthesized from banana stem (Zn-BS-CA) have outstanding characteristics such as high specific surface area (up to 115 m2/g), diverse pore shapes, high porosity of the material, and low bulk specific gravity. Characterization of Zn-BS-CA was shown through modern methods (scanning electron microscope, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray crystallography, energy-dispersive X-ray, and nitrogen adsorption–desorption isotherms). Zn-BS-CA reached a maximum oil adsorption capacity of 34,997 g/g and a specific capacitance of 74 F/g for Zn-BS-CA pyrolyzed at 700 °C (Zn-BS-CA700). More importantly, Zn-BS-CA 700 shows capacity retention of 95% after over 500 cycles. The above results indicate high oil adsorption and energy storage capabilities of Zn-BS-CA. [ABSTRACT FROM AUTHOR]

Electric vehicles need continuous monitoring of the energy supply all the time to provide the user with accurate information about the available energy. However, an increase in the power consumed by the monitoring system may cause a significant decrease in the vehicle’s autonomy. This letter presents a monitoring and estimation system for an electric car with a hybrid energy supply based on supercapacitors and batteries based on an embedded system capable of monitoring the general current, the current from the battery system, the voltage in the battery system, the voltage in the supercapacitor system, estimating the value of the state of charge from batteries, and showing the measurements to the user with an OLED display. The proposed system performs similarly in the estimation but decreases the energy consumption by 99.9% concerning the laboratory systems. [ABSTRACT FROM AUTHOR]

Activated carbon fibers (ACFs) were synthesized using a straightforward two-step process from dryer lint microfibers in a self-generated atmosphere. During pyrolysis and activation, a CO/CO2 environment was created based on the Boudouard equilibrium. The resulting ACFs showed a high specific surface area (1720 m2/g), a suitable pore size distribution, and good electrical conductivity (0.34–0.36 S/cm), promoting rapid ion transfer. ACFs demonstrated a high specific capacitance of 156.2 at 0.9 V and 180.3 F/g at 1 V. Notably, ACFs demonstrated outstanding rate capability with a power density exceeding 35 kW/kg, along with an extended cycle life of at least charge/discharge 104 cycles. These results are comparable to methods involving tube furnaces under inert gas with controlled heating ramps. [ABSTRACT FROM AUTHOR]

High-performance energy storage devices, such as portable electronic devices and electrically powered cars, need high electrochemical performances (energy and power densities). Supercapacitors are high-performance energy storage devices that have high specific capacitances and power densities. A new electrode design is compulsory to reach the target. So, its surface morphology, surface area, pore structures and charge carrier properties can be controlled to obtain a high-performance energy storage devices. In this study, bicyclo (2.2.1)-hept-5-en-2-carboxylic acid was chemically synthesized for use as a dopant in electrode materials. Furthermore, graphene oxide (GO) was synthesized by the modified Hummers method. The functional end groups of GO were activated by the acid dopant. Activated carbon (AC) was used as an electrode component for the biomass material of walnut sheels. AC/GO/acid was formed as a slurry using N-methyl-2-pyrrolidone. This mixture was electropolymerized with a thiophene (Th) monomer on an Au electrode with a 3-electrode system by the CV method. After removing the AC/GO/acid/PTh active materials on the Au electrode (called as C-1; C-2; C-3 with changing of acid content in the nanocomposite), the electrode was fabricated as a symmetrical 2 electrode supercapacitor device. Each component of the active materials was characterized by solid-state conductivity, SEM–EDX, FTIR-ATR, TGA-DTA, and BET analyses. Moreover, the electrochemical performance of supercapacitors, including CR2032 coin cells, was tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods. The highest specific capacitance was obtained at Csp = 743.70 F/g at 2 mV/s for AC/GO/PTh nanocomposite (C-4), which does not contain a dopant agent (acid). The highest conductivity was observed as σ = 2.61 × 10−5 S/cm in the highest acid content (18%) in the nanocomposite for C-3. The conductivity of C-3 is ~ 13.0 times greater than that of C-4. In addition, long-term stability tests (1000 and 5000 cycles) and equivalent circuit model analysis (Randless circuit, (Rs(CRct))) were carried out with 4 different composite materials for supercapacitor devices. [ABSTRACT FROM AUTHOR]

In this study, we explore the multifaceted applications of poly(methyl acrylate) (PMAc)-based composites, specifically focusing on their use as an efficient electrocatalyst for water splitting and a high-capacity supercapacitor. After a synthesis step, a characterization study (SEM, TEM, XRD, and Raman spectroscopy) was performed, and based on TEM results, a consistent pattern of small, uniform, and narrowly distributed Pd NPs within the range of 5–10 nm was observed. Also, other analyses confirmed the successful synthesis of PMAc-based composites. Through meticulous experimentation, the electrocatalytic performance of Pd/PMAc-graphene-carbon nanotube (Pd/PMAc-g-CNT) composites was evaluated against that of traditional Pd/PMAc catalysts. Tafel slope analysis was conducted to assess the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) efficiencies, where Pd/PMAc-g-CNT composites demonstrated significantly lower Tafel slopes of 274.53 mV dec⁻1 for OER and 389.91 mV dec⁻1 for HER. This indicates a superior electrocatalytic activity, enhancing the water splitting process. Furthermore, the same composite showcased an impressive specific capacitance of 132.3 F g⁻1 at a current density of 0.5 A/g, markedly surpassing the performance of the Pd/PMAc catalyst. This exceptional capacitance underlines its potential as a high-efficiency energy storage material. The novelty of this research lies in the synergistic integration of PMAc with graphene and carbon nanotubes to fabricate a dual-functional material. This composite not only excels in electrochemical catalysis for energy conversion but also demonstrates remarkable energy storage capabilities. The Pd/PMAc-g-CNT composite, therefore, emerges as a promising candidate for advancing supercapacitor technology and the electrocatalytic efficiency of water splitting, highlighting its dual utility in renewable energy systems. [ABSTRACT FROM AUTHOR]

In the present work, rare earth metal oxides composed of cerium tungstate/polyaniline (Ce2(WO4)3/PANI) composites were prepared by an in situ chemical oxidative polymerization process and their supercapacitive behavior was evaluated. The structural and morphological properties of the Ce2(WO4)3/PANI composites were characterized via spectral and analytical techniques. X-ray diffraction revealed that the two prominent peaks for Ce2(WO4)3 and PANI located at 2θ = 28.3° and 25.4° were in good accordance with the observed 2θ values in Ce2(WO4)3/PANI composite. Field-emission scanning electron microscopy (FESEM) studies of Ce2(WO4)3/PANI had a nano-spherical interconnected with a layer-like morphology, which results in a rapid electron exchange. Electrochemical analysis revealed that Ce2(WO4)3/PANI exhibited an increased supercapacitor electrode response with a significant specific capacity (Cs) of 399 C g−1 at 1 Ag−1 and exhibited a remarkable capacity retention of 90.5% even after 3000 galvanostatic charge-discharge (GCD) cycles with 84% columbic efficiency, suggesting its promising electrode material for SCs. [ABSTRACT FROM AUTHOR]

The pursuit for high-performance supercapacitor electrodes has received considerable interest, fueled by the urgent need for reliable energy storage solutions in the face of the impending exhaustion of fossil fuels and the necessary transition towards renewable resources. Herein, CoWO4/MWCNT nanocomposite (NCs) are grown on Ni-foam substrate via a facile hydrothermal process. The CoWO4 nanoparticles (NPs) anchored with 1D-MWCNT on the Ni-foam substrate were confirmed through XRD, FT-IR, and SEM analysis. The XRD analysis showcased CoWO4 NP size of about 54 nm; also, the SEM findings demonstrated 20.6 ± 4 nm-sized aggregated CoWO4 NPs. Interestingly, the CoWO4/MWCNT NCs exhibited a high specific capacity of 115 C g−1 at 1 Ag−1, with 98% retention even after 5000 cycles at 5 A g−1. Notably, the dielectric properties were studied, showing a dielectric constant of 73.56 for CoWO4 and 82.24 for CoWO4/MWCNT at 1 MHz, suggesting potential for ferroelectric applications. [ABSTRACT FROM AUTHOR]

Binary transition metal chalcogenides and reduced graphene oxide exhibit significant potential for energy storage devices due to their superior electronic conductivity and capacity, surpassing that of single-metal sulfides, owing to their more extensive redox reactions. In this report, we introduce a novel synthesis method for producing a mixed-phase MnSe2/CoSe2 nanocomposite wrapped with reduced graphene oxide (rGO) sheets, designed specifically for supercapacitor applications. The MnSe2/CoSe2 hybrid material was synthesized using an ultrasonic assisted hydrothermal technique, followed by the preparation of the rGO/MnSe2/CoSe2 hybrid composite. The structural characterization was conducted employing x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Raman techniques. Brunauer–Emmett–Teller (BET) analysis demonstrated a significant specific surface area (66.5 m2/g) and a pore size distribution of 28.4 nm in rGO-MnSe2/CoSe2. The interconnected ultrathin rGO nanosheets and conductive carbon layer contributed to the exceptional conductivity and stability achieved by the rGO/MnSe2/CoSe2 composite electrode. The electrochemical performance was assessed using a three-electrode setup in a 3 M KOH solution, with nickel foam as the current collector. The working electrode, consisting of rGO/MnSe2/CoSe2, acetylene black and PVDF in an 80:15:5 weight ratio, demonstrated specific capacitance of 1214 F g−1 and cycling stability of 88% retention after 5000 cycles at 1 A g−1. An asymmetric supercapacitor, constructed using a tailored electrode composition, achieved energy density of 28.6 Wh kg−1 at 2100 W kg−1 and high power density of 888 W kg−1 at 49.7 Wh kg−1. [ABSTRACT FROM AUTHOR]

Biopolymer composite electrolytes consisting of cellulose acetate and magnesium perchlorate with different weight percent (wt.%) of Zinc Oxide fillers were prepared using the standard solution cast technique. The effect of incorporating various amounts of ZnO fillers in our composite electrolytes was investigated for their electrical and structural properties, and ion transference numbers. The ionic conductivity of 40 wt.% ZnO filler was found to be 8.75× 10−4 S/cm at 30 °C along with a 4.2 V electrochemical stability window. The ion transference number has been found to be 0.97 for CA + 40 wt.% of Mg(ClO4)2 + 40 wt.% with ZnO fillers. Furthermore, the electrochemical performances of the prepared electrolytes have also been investigated. The fabricated cell with this electrolyte shows an enhanced energy and high-power density of 2.78 Wh/Kg and 1000 W/Kg, respectively. An increase in the above-mentioned densities may be attributed to the high ionic conductivity ZnO fillers in the biopolymer matrix. Additionally, it shows 100% capacitance retention along with high coulombic efficiency after the 129th cycle. [ABSTRACT FROM AUTHOR]

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The simple and cost‐effective co‐precipitation method is used for the synthesis of pure Co3O4 and 5% Sn‐doped Co3O4 nanoflakes. Crystallographic parameters, chemical composition, morphological properties, optical properties, and surface area are analyzed using X‐ray diffraction data (XRD), Fourier transform infrared spectroscopy (FT‐IR), Raman analysis, UV–vis, field emission scanning microscopy, energy‐dispersive X‐ray analysis, and Brunauer–Emmett–Teller (BET), respectively. By using cyclic voltammetry and electrochemical impedance spectroscopy in a 2 m KOH electrolyte, the electrochemical characteristics of both pure and 5% Sn‐doped Co3O4 are verified. The sample results show that the presence of Sn2+ has an impact on surface area, band gap, specific capacitance, and electrochemical performance of Co3O4. According to XRD data, synthetic material has a cubic structure. The surface area of the sample is scrutinized using BET which exhibits a higher surface area of 1084.998 m2 g−1 than pure Co3O4 (92.842 m2 g−1) demonstrating that enhancement in surface area as dopant concentration increases. It is observed that porous 5% Sn‐doped Co3O4 nanoflakes has the higher specific capacitance, i.e., 203.6 F g−1 with a high surface area. It is well noticed that drastic change in specific capacitance with 5% Sn doping. These observations and experiments reveal that designed electrode is a promising candidate for supercapacitor application. [ABSTRACT FROM AUTHOR]

Organic potassium salts are the promising green activators for synthesizing porous carbon materials for energy storage. Herein, we report the synthesis of hierarchical porous carbon material derived from the mixture of soluble starch and ethylenediaminetetraacetic acid dipotassium salt dihydrate (EDTA‐2K) via carbonization and activation strategy. The sample is used as supercapacitors electrode, which exhibits superior mass specific capacitance (307.3 F g−1 at 1 A g−1), good rate performance (255.0 F g−1 at 10 A g−1), and excellent stability (retaining 83 % after 15000 cycles). This enhanced electrode performance is mainly due to the high specific surface area, the heteroatom co‐doping providing pseudo‐capacitance and the improved electronic conductivity. In addition, the asymmetric supercapacitor device shows a high energy density of 15 Wh kg−1 at the power density of 800 W kg−1 and capacitance retention of 90 % after 12000 cycles. [ABSTRACT FROM AUTHOR]

The present research work reported the study of nanocomposites of undoped and Mg‐doped ZnO with CNT as electrode materials for supercapacitor application. The undoped ZnO/CNT and Mg‐doped ZnO/CNT nanocomposites (i.e., 10 % Mg‐doped and 20 % Mg‐doped) were synthesized using a cost‐effective blending‐assisted hydrothermal method. The morphological (FESEM & TEM) studies revealed that the diameter of CNT was ~7 nm and the ZnO nanoparticles were spherical in shape with an average particle size of ~5 nm. In addition, it was also found that 10 % Mg‐ZnO and 20 % Mg‐ZnO had a sheet‐like structure. XRD and FTIR studies further confirmed the successful doping of Mg in ZnO and CNT nanocomposites. BET analysis showed that the value of specific capacitance increased with the increase in surface area. Further, the electrochemical performance of these nanocomposites revealed that the higher doping percentage, 20 % Mg‐ZnO/CNT nanocomposite achieved the highest specific capacitance value i.e., 458.5 F/g at 0.1 A/g current density in 3M H2SO4 electrolytic solution, having a retention of 99.8 % after 12,00 long cycles. In addition, the charge storage mechanism revealed that the as‐synthesized nanocomposites showed both the diffusion‐controlled and capacitive‐controlled behaviors. Thus, a higher value of specific capacitance with excellent cyclic stability indicated the higher efficiency of Mg‐doped ZnO/CNT nanocomposite for future supercapacitor applications. [ABSTRACT FROM AUTHOR]

The integration of fuel cell device and supercapacitor device into a singular hybrid power source at the electrode level can make the best use of the advantages of each individual device and more importantly, eliminate the energy loss by virtue of the conversion of chemical energy to electric energy on electrocatalyst material and the storage of electric energy on energy storage material simultaneously. To avoid the use of noble metal electrocatalyst and exploit the dual electrocatalytic and capacitive function of polyaniline, a noble-metal-free fuel cell-supercapacitor hybrid power source employing polyaniline electrode as both anode and cathode is rationally constructed. Based on electrochemical in-situ Raman spectroscopy, this work proposes that the open circuit potential (OCP) of polyaniline electrode is a simple and quick indicator of the redox state of polyaniline. After carefully selecting the fuel and carbon-based support, it is found that the ascorbic acid fuel and the carbon fiber cloth supported polyaniline contributes to the lowest OCP threshold in the anode, and thus the fastest self-charge and largest stabilized open circuit voltage of hybrid power source. The hybrid power source can be self-charged to 0.32 V and yield a peak power density of 0.21 mW cm−2. [Display omitted] • Noble-metal-free fuel cell-supercapacitor hybrid power source on electrode level. • Dual electrocatalytic and capacitive function of polyaniline. • Open circuit potential of electrode can represent the redox state of polyaniline. • Widening redox state threshold enhances the performance of hybrid power source. • Self-charge and discharge performance of hybrid power source. [ABSTRACT FROM AUTHOR]

N, S co-doping three-dimensional (3D) honeycomb-like porous carbon derived from pinecone (NSZPC) was fabricated through preoxidation and subsequent calcination in the presence of zinc chloride and thiourea. Owing to the synergistic effect of the three-dimensional hierarchical porous structure and N, S co-doping, NSZPC exhibited excellent lithium-ion storage performance. Specifically, the reversible capacity of the target product (NSZPC, 827.6 mAh·g−1 at 1 A g−1) was significantly higher than that of carbon prepared through direct calcination of pinecone carbon and thiourea (NSPC, 133.7 mAh·g−1 at 1 A g−1) and that of carbon obtained by calcining pinecone carbon in ZnCl 2 molten salt (ZPC 375.8 mAh·g−1at 1 A g−1). Even at a high current density of 10 A g−1, NSZPC still delivered a high reversible capacity of 445.2 mAh·g−1, while NSPC and ZPC only exhibited 8.5 and 84.0 mAh·g−1, espectively. Moreover, the asymmetric supercapacitor based on NSZPC in 6 M KOH electrolyte delivered an excellent specific capacitance of 468.0 F g−1 at 200 mA g−1. After ultra-long cycles of 10,000, the capacitance retention rate remained at 88.5%, indicating superior cycling stability. In addition, the symmetric supercapacitor (NSZPC//NSZPC) exhibited high energy and power densities of 25.3 W h·kg−1 and 9998 W kg−1, respectively. Thus, the present work provides an efficient and low-cost strategy to prepare pinecone-based porous carbon as potential electrodes for LIBs and SCs and offers a high-quality route for alleviating environmental pollution. [Display omitted] • Pinecone-derived porous carbon was fabricated through preoxidation and subsequent calcination in molten salt. • The synergistic effect of three-dimensional porous structure and N, S co-doping reinforced energy storage performance. • The electrode was suitable for application in Li-ion battery and supercapacitor. [ABSTRACT FROM AUTHOR]

An economically and environmentally sustainable course of action to address energy crisis concerns is to recycle discarded PET (polyethylene terephthalate) plastics into value-added products for the aforementioned application. Herein, a high surface area Cu-metal organic framework (Cu-MOF) has been synthesized through an economically feasible approach using trash PET plastic. However, electrochemical properties of pristine MOFs are hindered due to their poor stability and low intrinsic conductivity. Hence, high-performance nanocomposites of Cu-MOF with conducting polymers like PANI (polyaniline) and PPy (polypyrrole) have been synthesized via an in situ hydrothermal technique. PANI and PPy not only improve the conductivity of the nanocomposite but also create additional MOF-PANI-MOF transport channels, which ensures effective electrolyte ion transportation and hence enhances the overall electrochemical performance. Cu-MOF/PANI and Cu-MOF/PPy nanocomposites exhibit high specific capacitances of 160.5 and 132.5 F/g, respectively, at a current density of 0.5 A/g, which is more than that of pristine Cu-MOF (104.8 F/g). Furthermore, asymmetric hybrid supercapacitor devices (Cu-MOF//Cu-MOF/PANI and Cu-MOF//Cu-MOF/PPy) have been assembled that have shown immense potential as energy storage devices. The Cu-MOF//Cu-MOF/PANI hybrid device delivered a high energy density of 51.4 Wh/kg at 474 W/kg power density with outstanding cyclic stability, attenuating only 6.6% after 10 000 charge–discharge cycles. [ABSTRACT FROM AUTHOR]

Our study presents a facile hydrothermal approach for synthesizing NiMn2O4 and NiMn2O4/C nanostructures (NSs) intended for implementation as electrode materials in high-performance supercapacitors. The NiMn2O4 and NiMn2O4/C NSs synthesized via the hydrothermal method were comprehensively characterized using XRD, FE-SEM, FT-IR, XPS, and BET. Subsequently, the electrochemical performance of both NiMn2O4 and NiMn2O4/C was evaluated via CV, GCD, and EIS in 2 M KOH aqueous electrolyte. Our results demonstrate that the NiMn2O4/C electrode revealed a substantial specific capacitance/capacity of 789.3 F g–1/552.5 C g–1 at a scan rate of 5 mV s–1. Furthermore, the NiMn2O4/C electrode maintained a specific capacity retention of less than 4% after 5000 cycles. When coupled with an activated carbon (AC) electrode, the NiMn2O4/C//AC configuration exhibited a notable specific capacitance/capacity of 101.6 F g–1/162.5 C g–1, accompanied by a high energy density of 36.11 W h kg–1 at a power density of 1000 W kg–1, and sustained excellent cyclic stability (84% retention after 5000 cycles). Additionally, electrochemical analysis revealed an overpotential of 199 mV at 50 mA cm–2 and a minimal Tafel slope of 89 mV dec–1 for the oxygen evolution reaction (OER), suggesting the suitability of the NiMn2O4/C electrode for alkaline water electrocatalysis. Prolonged chronopotentiometry investigations at 100 mA cm–2 over 24 h further demonstrated a remarkable 97.3% retention of the OER activity. [ABSTRACT FROM AUTHOR]

Supercapacitors (SCs) based on hierarchical nanoporous framework composite materials and aqueous electrolytes are recent interests for the researchers. The structure of UiO-66 exhibits extraordinary stability and high specific surface area, but the specific capacitance of UiO-66 (139.4 F g–1 at 2 A g–1) is limited due to its moderately conducting nature. Therefore, we report a method to modify UiO-66 with pineapple peel derived activated carbon (PA-AC) to form a facile composite. Owing to the high specific surface area and good conductivity of the UiO-66/PA-AC composite, a high specific capacitance of 295.9 F g–1 at 2 A g–1 has been achieved and is well suited for supercapacitor applications. At the maximum charging voltage range of 0–1.8 V, the UiO-66/PA-AC//UiO-66/PA-AC symmetrical SC delivered a maximum energy density of 29.6 Wh kg–1 at a power density of 170 W kg–1. After 5000 repeated charge–discharge cycles at 30 A g–1, the specific capacitance of the device increased from 100% to 120% of its initial specific capacitance. This study emphasized the potential importance of incorporating MOFs into pores of biowaste derived carbon as a strategy for enhancing the charge storage kinetics of moderately conducting MOFs. [ABSTRACT FROM AUTHOR]

Noble metal nanoparticles incorporated in hybrid nanocomposites are considered as promising candidates for electrochemical applications owing to their physicochemical properties. In this work, we demonstrated the preparation of Fe2O3/rGO nanocomposite by hydrothermal method, followed by in situ Ag binding synthesis for the fabrication of hybrid nanocomposite (Ag/α-Fe2O3/rGO). The crystallographic structure of the hybrid nanocomposite is examined by X-ray diffraction (XRD) analysis which confirms the characteristics of Ag, Fe2O3, and rGO. The microscopic studies and energy-dispersive X-ray analysis (EDS) spectra confirmed the presence and formation of hybrid nanostructures. Raman analysis results further corroborate the formation of composite with significant D and G bands in Fe2O3/rGO and Ag/α-Fe2O3/rGO samples, which follow XRD results. Cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) studies were carried out to analyze the faradaic capacitor behavior. A specific capacitance of 209.09 F/g was observed by GCD studies for Ag/α-Fe2O3/rGO composites at a current density of 1 A/g, which exhibited good capacitance retention of 94% for 5000 cycles at 7 A/g. Furthermore, the Ag/α-Fe2O3/rGO electrode was used for the electrochemical detection of nitrate ions in soil by utilizing an ion-selective membrane over the surface of the Ag/α-Fe2O3/rGO electrode. The fabricated nanocomposite electrode showed a significant change in the peak current values with the concentration of nitrate in a linear range from 10 to 450 μM with the sensitivity to be calculated 1.426 μA μM−1 cm−2 and limit of detection (LOD) calculated to be 0.18 μM. The reproducibility and interference studies showed a promising result to be utilized for detecting nitrate ions in soil and in real-time applications. [ABSTRACT FROM AUTHOR]

MXene is a novel two-dimensional layered nanomaterial with a very large specific surface area and abundant surface functional groups, endowing it with unique physical and chemical properties. MXene can be compounded with other functional materials to significantly improve the performance of MXene composites or broaden their application scope. Meanwhile, with the development of flexible composite preparation technology, it has promoted the continuous expansion of its application fields. The introduction and combination of different materials can improve the performance of flexible composites and make them have a broader application prospect. In recent years, researchers have started preparing MXene materials as flexible composites for applications such as supercapacitors, sensors, electromagnetic shielding and thermal management. This paper gives a brief introduction to flexible composites and MXene materials, reviews the applications of MXene based flexible composites in various fields as well as the research progress, and provides an outlook on their future development direction. [ABSTRACT FROM AUTHOR]

Wood‐derived carbons demonstrate great potential as self‐standing electrodes in energy storage/conversion applications, including supercapacitors and water‐splitting devices. However, the key challenge remains the rational customization of surface functionalities for optimized performance. This study introduces an innovative approach to self‐standing wood‐derived carbons with tailored nitrogen and metal functionalities. In contrast to traditional impregnation techniques, which offer limited precision in surface modification, this approach entails the intentional attachment of amidoxime groups to the wood substrates. These groups serve as nitrogen sources, and create abundant surface anchoring sites for metal ions due to the chelation between the amidoxime groups and metals. The resulting carbons feature uniform and high dispersion of nitrogen and metal functionalities, along with a distinctive hierarchical porosity combining interconnected open channels with abundant mesopores. As a proof‐of‐concept, different metals are incorporated (i.e., Mn, Co, Ni) into the amidoximated‐wood precursors, and the resulting self‐standing carbons showcase excellent performance in both supercapacitors and water‐splitting applications. Leveraging the specific chelating ability of amidoxime groups toward metal ions, this strategy holds great potential as a generic approach to systematically tailoring the surface functionalities of carbon‐based materials for various electrochemical energy storage/conversion processes. [ABSTRACT FROM AUTHOR]

Here, the hierarchical mesoporous-activated carbon particles obtained by KOH activation from pistachio shell wastes are modified by both the sulfonation process and CuO doping by hydrothermal heating (CuO@S-doped PSAC) for use as a supercapacitor. It is predicted that the electrochemical performance of the porous carbon electrode material obtained by such CuO doping and sulfonation process will be significantly increased with increased Faradaic capacitance. The electrochemical performance of CuO@S doped PSAC composite is systematically investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) in the presence of 1 M H2SO4, 1 M Na2SO4, and 1 M NaOH as electrolytes. The CuO@S doped PSAC-based electrode shows excellent stability with high specific capacitance up to 397.16 F/g at 0.1 A/g and 92.64% retention. Furthermore, FTIR, SEM, XRD, EDS, and nitrogen adsorption/desorption analyses are used for the characterisation of the obtained composites. Based on a significant supercapacitor performance, the synthesis strategy of carbon-based electrode material containing sulfonation and CuO modifications derived from agricultural biomass waste material is predicted to be a valuable example. [ABSTRACT FROM AUTHOR]

Three-dimensional interconnected mesoporous nanoflakes of amorphous Ni-Mo-Co trimetallic hydroxides were successfully deposited on a Ni foam (NF) using a facile, environmentally friendly, and scalable electrochemical deposition method. The elemental composition of the nanoflakes, including Ni2+, Mo6+, and Co2+, was characterized by X-ray photoelectron spectroscopy (XPS), while the morphology and particle size of the synthesized nanomaterials were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Ni-Mo-Co trimetallic hydroxides on NF were employed as binder-free electrodes for supercapacitors. The Ni-Mo-Co trimetallic hydroxides with a Ni/Mo/Co ratio of 1/1/0.4 exhibited outstanding long-term cyclability over 5000 cycles, with a high reversible specific capacitance of 2700 F g−1 and a high capacitance retention of 96.63% at 10 A g−1. Furthermore, they demonstrated excellent rate performance, maintaining a capacitance of 2429 F g−1 at a current of 50 A g−1, which corresponds to approximately 80% capacitance retention compared to the capacitance at 2 A g−1. The superior performance of these Ni-Mo-Co trimetallic hydroxides can be attributed to their mesoporous hierarchical architecture, which provides large open spaces between the interconnected nanoflakes, numerous electroactive surface sites, facile electron transmission paths, and the synergistic effects of the trimetallic components. These findings demonstrate that Ni-Mo-Co trimetallic hydroxides are promising electrode materials, offering both high capacitance and long-term cyclability for supercapacitors. [ABSTRACT FROM AUTHOR]

New materials and the interactions between them are the basis of novel energy storage devices such as supercapacitors and batteries. In recent years, because of the increasing demand for electricity as an energy source, the development of new energy storage materials is among the most actively studied topics. Conductive polymers (CPs), because of their intrinsic electrochemical activity and electrical conductivity, have also been intensively explored. While most of the high capacitance reported in the literature comes from hybrid materials, for example, conductive polymers composed of metal oxides and carbon materials, such as graphene and carbon nanotubes, new chemistry and the 3D structure of conductive polymers remain critical. This comprehensive review focuses on the basic properties of three popular conductive polymers and their composites with carbon materials and metal oxides that have been actively explored as energy storage materials, i.e., polypyrrole (PPy), polyaniline (PANi), and polythiophene (PTh), and various types of electrolytes, including aqueous, organic, quasi-solid, and self-healing electrolytes. Important experimental parameters affecting material property and morphology are also discussed. Electrochemical and analytical techniques frequently employed in material and supercapacitor research are presented. In particular, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are discussed in detail, including how to extract data from spectra to calculate key parameters. Pros and cons of CP-based supercapacitors are discussed together with their potential applications. [ABSTRACT FROM AUTHOR]

Designing efficient electrode materials is necessary for supercapacitors but remains highly challenging. Herein, cobalt sulfide with crystalline/amorphous heterophase (denoted as Co(Al)S) derived from an Al metal–organic framework was constructed by ion exchange/acid etching and subsequent sulfidation strategy. It was found that rational sulfidation by adjusting the sulfur source concentration to a suitable level was favorable to form a 3D nanosheet-interconnected network architecture with a large specific surface area, which promoted ion/electron transport and charge separation. Benefiting from the features of the unique network structure and heterophase accompanied by aluminum, nitrogen and carbon coordinated in amorphous phase, the optimal Co(Al)S(10) exhibited a high specific capacity (1791.8 C g−1 at 1 A g−1), an outstanding rate capability and an excellent cycling stability. Furthermore, the as-assembled Co(Al)S//AC device afforded an energy density of 72.3 Wh kg−1 at a power density of 750 W kg−1, verifying that the Co(Al)S was a promising material for energy storage devices. The developed scheme is expected to promote the application of MOF-derived electrode materials in electrochemical energy storage and conversion fields. [ABSTRACT FROM AUTHOR]

The development of photo-/electro-chemical and flexible electronics has stimulated research in catalysis, informatics, biomedicine, energy conversion, and storage applications. Gels (e.g., aerogel, hydrogel) comprise a range of polymers with three-dimensional (3D) network structures, where hydrophilic polyacrylamide, polyvinyl alcohol, copolymers, and hydroxides are the most widely studied for hydrogels, whereas 3D graphene, carbon, organic, and inorganic networks are widely studied for aerogels. Encapsulation of functional species with hydrogel building blocks can modify the optoelectronic, physicochemical, and mechanical properties. In addition, aerogels are a set of nanoporous or microporous 3D networks that bridge the macro- and nano-world. Different architectures modulate properties and have been adopted as a backbone substrate, enriching active sites and surface areas for photo-/electro-chemical energy conversion and storage applications. Fabrication via sol–gel processes, module assembly, and template routes have responded to professionalized features and enhanced performance. This review presents the most studied hydrogel materials, the classification of aerogel materials, and their applications in flexible sensors, batteries, supercapacitors, catalysis, biomedical, thermal insulation, etc. [ABSTRACT FROM AUTHOR]

How to address the destruction of the porous structure caused by elemental doping in biochar derived from biomass is still challenging. In this work, the in-situ nitrogen-doped porous carbons (ABPCs) were synthesized for supercapacitor electrode applications through pre-carbonization and activation processes using nitrogen-rich pigskin and broccoli. Detailed characterization of ABPCs revealed that the best simple ABPC-4 exhibited a super high specific surface area (3030.2–3147.0 m2 g−1) and plentiful nitrogen (1.35–2.38 wt%) and oxygen content (10.08–15.35 wt%), which provided more active sites and improved the conductivity and electrochemical activity of the material. Remarkably, ABPC-4 showed an outstanding specific capacitance of 473.03 F g−1 at 1 A g−1. After 10,000 cycles, its capacitance retention decreased by only 4.92% at a current density of 10 A g−1 in 6 M KOH. The assembled symmetric supercapacitor ABPC-4//ABPC-4 achieved a power density of 161.85 W kg−1 at the maximum energy density of 17.51 Wh kg−1 and maintained an energy density of 6.71 Wh kg−1 when the power density increased to 3221.13 W kg−1. This study provides a mixed doping approach to achieve multi-element doping, offering a promising way to apply supercapacitors using mixed biomass. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) receive wide attention owing to their high specific surface area, porosity, and structural designability. In this paper, ZC-Ru and ZC-Cu electrodes loaded with monatomic Ru and Cu doped with nitrogen were prepared by pyrolysis, ion impregnation, and carbonization process using ZIF-8 synthesized by static precipitation as a precursor. ZC-Cu has a high specific surface area of 859.78 m2 g−1 and abundant heteroatoms O (10.04%) and N (13.9%), showing the specific capacitance of 222.21 F g−1 at 0.1 A g−1 in three-electrode system, and low equivalent series resistance (Rct: 0.13 Ω), indicating excellent energy storage capacity and electrical conductivity. After 10,000 cycles at 1 A g−1 in 6 M KOH electrolyte, it still has an outstanding capacitance retention of 99.42%. Notably, symmetric supercapacitors ZC-Cu//ZC-Cu achieved the maximum power density and energy density of 485.12 W·kg−1 and 1.61 Wh·kg−1, respectively, positioning ZC-Cu among the forefront of previously known MOF-based electrode materials. This work demonstrates the enormous potential of ZC-Cu in the supercapacitor industry and provides a facile approach to the treatment of transition metal. [ABSTRACT FROM AUTHOR]

An integrated visual energy system consisting of conjugated polymer electrodes is promising for combining electrochromism with energy storage. In this work, we obtained copolymer bifunctional electrodes poly(3,6-dimethoxythieno[3,2-b]thiophene-co-2,3-dihydrothieno[3,4-b][1,4]dioxin-3-ylmethanol)(P(TT-OMe-co-EDTM)) by one-step electrochemical copolymerization, which exhibits favorable electrochromic and capacitive energy storage properties. Because of the synergistic effect of PTT-OMe and PEDTM, the prepared copolymers show better flexibility. Moreover, the morphology and electrochemical properties of the copolymers could be adjusted by depositing different molar ratios of 3,6-dimethoxythieno[3,2-b]thiophene (TT-OMe) and 2,3-dihydrothieno[3,4-b][1,4] dioxin-3-ylmethanol (EDTM). The P(TT-OMe-co-EDTM) electrodes realized a high specific capacitance (190 F/g at 5 mV/s) and recognizable color conversion. This work provides a novel and simple way to synergistically improve electrochromic and energy storage properties and develop thiophene-based conducting polymers for electrochromic energy storage devices. [ABSTRACT FROM AUTHOR]

In this study, a redox reaction is employed to synthesize manganese oxide (Mn3O4) nanoparticles using potassium permanganate as a precursor in the presence of diethyl amine. The structural characterization reveals the formation of the tetragonal phase of Mn3O4 nanoparticles with a space group of I41/amd. A free‐standing Mn3O4‐based paper electrode is fabricated and its electrochemical performances are investigated. The electrode exhibits a maximum specific capacitance value of ~353 F g−1 and an areal capacitance of ~530 mF cm−2 at a current density of 0.2 A g−1. A symmetric supercapacitor‐based device is also designed using Mn3O4 nanoparticles as an active material in a gel electrolyte configuration. The Mn3O4 device achieves specific and areal capacity values of ~208 mAh g−1 and 260 mA cm−2, respectively, at a current density of 0.3 A g−1. The device delivers maximum energy and power density values of ~104 Wh kg−1 and ~220 W kg−1, respectively, with ~92 % specific capacity retention at 0.3 A g−1 after 5000 cycles. The above results suggest that the Mn3O4‐based device has the potential for energy storage applications. [ABSTRACT FROM AUTHOR]

Integrating energy harvesters with energy storage devices helps enhance energy utilization efficiency. The requirement for external power sources in energy storage devices can also be addressed by the development of an all‐in‐one single system. Vegetable peels can be used as piezoelectric energy harvesters due to the generation of electric dipole within cellulose. The self‐discharge processes cause open circuit potential decay, resulting in a loss of energy stored within the cell. The self‐discharge rate can be controlled by using a piezoelectric separator. This work used garlic skins as a piezoelectric separator, which helped delay the self‐discharge rate. The supercapacitor using Ni−Mn oxide as positive and Fe−Ni sulfide/RGO as negative electrode materials was fabricated with garlic skin as a separator. The device was charged from an initial OCP of ~0.15–~0.37 V in ~ 4 sec by finger tapping. The OCP decay rate was reduced by~88 % compared to that of using the Whatmann separator. The fabricated Ni−Mn oxide RGO/garlic skin/FeS2 RGO exhibited ~72.2 W h kg−1 energy density at a power density of ~2 kW kg−1 in an operated potential window of ~2 V. This research provides a cost‐effective method for developing piezoelectric supercapacitor with low self‐discharge rate. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of poly(ethylene‐thiosuccinate) (PETS) using succinic anhydride and 1,2‐ethanedithiol monomers and investigates its electrochemical behavior as supercapacitor electrode material. The synthesized polymer's structure is designed so that to contain sulfur atoms in the main chain of polymer, as the sulfur containing polymers are among the interesting active compounds for fabricating of novel devices for energy storage with wider voltage window and increase the energy density. The cyclic voltammetry (CV) graphs show the supercapacitor behavior of the materials with the faradic charge storage mechanism. The triangular shape of the charge–discharge curves indicate the reversible performance of the PETS as an electrode material. To enhance the supercapacitive action of PETS, its nanocomposites including PETS/Norit (1:1), PETS/MWCNT (1:1) and PTES/MWCNT (1:1)/(1.5%, 3% and 5%) Ni2CoHCF (nickel‐cobalt hexacyanoferrate) is prepared. The results indicate that the PETS/MWCNT/0.15% Ni2CoHCF nanocomposite exhibits a specific capacity which is 7 times higher than that of the PETS/MWCNT (1:1) nanocomposite, when the current density is 0.05 mA.cm−2. Also, according to the Nyquist diagrams, by incorporating of 1.5% of Ni2CoHCF in the PETS/MWCNT (1:1) nanocomposite, its electrical resistance decreases significantly by about two times. Highlights: Poly(ethylene‐thiosuccinate) (PETS) made by succinic anhydride & ethanedithiolPETS/Norit or MWCNT/cubic Ni2CoHCF nanoparticles composites are preparedPETS/MWCNT composites as supercapacitor materials by Faradic storage mechanismPETS/1.5% Ni2CoHCF showed 0.0449 mF.cm−2 specific capacity at 0.01 mA.cm−2 [ABSTRACT FROM AUTHOR]

The preparation of high‐performance and fire‐safe electrolytes for flexible quasi‐solid‐state supercapacitors is challenging. In this work, a novel fire‐safe and multifunctional deep eutectic solvent gel (DESG) is fabricated using acrylic acid and urea as hydrogen bond donors and choline chloride as a hydrogen bond acceptor. DESG shows a high ionic conductivity (0.552 S m−1), good electrochemical performance (specific capacitance: 106.8 F g−1), and a wide operating temperature range (−20–90 °C), being a promising candidate for flexible solid‐state supercapacitors. Furthermore, it exhibits a good thermoelectric conversion capability (Seebeck coefficient: 1.56 mV K−1), being ideal for thermoelectric capacitors and fire‐warning sensors. The prepared DESG rapidly self‐extinguishes after removal from fire, reaching a limiting oxygen index value of 38.0% and demonstrating its excellent flame retardancy. In addition, DESG has a good self‐healing performance (healing efficiency of 84.3%). The work provides new insights into the preparation and application of high fire‐safety and multifunctional eutectogels for flexible quasi‐solid‐state supercapacitors. [ABSTRACT FROM AUTHOR]

Nanoporous metals, fabricated via dealloying, offer versatile applications but are typically limited to unimodal porous structures, which hinders the integration of conflicting pore‐size‐dependent properties. A strategy is presented that exploits the homologous temperature (TH)‐dependent scaling of feature sizes to generate hierarchical porous structures through multistep dealloying at varied TH levels, adjusted by altering dealloying temperatures or the material melting points. This technique facilitates the creation of monolithic architectures of bimodal porous nickel and trimodal porous carbon, each characterized by well‐defined, self‐similar bicontinuous porosities across distinct length scales. These materials merge extensive surface area with efficient mass transport, showing improved current delivery and rate capabilities as electrodes in electrocatalytic hydrogen production and electrochemical supercapacitors. These results highlight TH as a unifying parameter for precisely tailoring feature sizes of dealloyed nanoporous materials, opening avenues for developing materials with hierarchical structures that enable novel functionalities. [ABSTRACT FROM AUTHOR]