Three-electrode Configuration Research Articles

Integrated capture and solar-driven utilization of CO2 from flue gas and air

Integrated capture and solar-driven utilization of CO2 from flue gas and air

A Facile Two-Step Hydrothermal Synthesis of Co(OH)2@NiCo2O4 Nanosheet Nanocomposites for Supercapacitor Electrodes

The composites of NiCo2O4 with unique structures were substantially investigated as promising electrodes. In this study, the unique structured nanosheets anchored on nickel foam (Ni foam) were prepared under the hydrothermal technique of NiCo2O4 and subsequent preparation of Co(OH)2. The Co(OH)2@NiCo2O4 nanosheet composite has demonstrated higher specific capacitances owing to its excellent specific surface region, enhanced rate properties, and outstanding electrical conductivities. Moreover, the electrochemical properties were analyzed in a three-electrode configuration to study the sample material. The as-designed Co(OH)2@NiCo2O4 nanosheet achieves higher specific capacitances of 1308 F·g−1 at 0.5 A·g−1 and notable long cycles with 92.83% capacity retention over 6000 cycles. The Co(OH)2@NiCo2O4 nanosheet electrode exhibits a long life span and high capacitances compared with the NiCo2O4 and Co(OH)2 electrodes, respectively. These outstanding electrochemical properties are mainly because of their porous construction and the synergistic effects between NiCo2O4 and Co(OH)2. Such unique Co(OH)2@NiCo2O4 nanosheets not only display promising applications in renewable storage but also reiterate to scientists of the unlimited potential of high-performance materials.

Microwave-assisted design and fabrication of rare earth doped NiMoO4: An admirable electrode material in redox electrolytes with excellent power density for high-end energy storage systems

In the recent advancement of energy storage, electrode materials delivering high energy density and the capability to deliver noteworthy power compared to batteries are considered to be promising materials. In this study, hierarchical-structured NiMoO4 and various concentrations of Ce rare earth metal doped NiMoO4 materials have been synthesized by microwave-assisted combustion route. Their structural, morphological, and spectroscopical characteristics have been studied using different characterization and analytical techniques. The α to β-NiMoO4 phase transformation with the same crystal structure has been confirmed after the addition of 5% Ce dopant. The crystallite size, cell volume, and particle size of the β-NiMoO4 seems to be minimal with maximum dislocation density compared to the prepared α-NiMoO4 samples. The initial nanospheres are clustered in different orientations to form different morphological structures. All the samples have been evaluated as electrodes for highly efficient electrochemical supercapacitors. The 5%-Ce doped NiMoO4 electrode has revealed an extraordinary supercapacitive performance showing excellent specific capacitance of 3101.12 Fg‐1 at 1 mA current with good retentivity of 97.65% after 5000 cycles in a three-electrode configuration, which is six times higher value than the prepared pristine NiMoO4 (478.78 Fg‐1). Besides, an asymmetric supercabattery device has been fabricated utilizing NiMoO4‐5% Ce electrode and activated carbon as positive and negative electrodes in a two-electrode configuration. It displayed a fascinating energy density of 29.2 W h kg−1 even at high current density of 5 mA. Prominently, the supercabatteries device showed an admirable 80.55% long-lasting cycling performance retained after 10,000 cycles.

Study of Predominant Dynamics on the O3-Type Layered Transition-Metal Oxide Cathode by Electrochemical Impedance Spectroscopy for Sodium-Ion Batteries.

The layered transition metal oxides (NaxTMO2) are the most attractive cathode options for the rechargeable sodium-ion batteries (SIBs) owing to their high specific capacity, outstanding sodium desorption ability, and high average operating voltage. However, the kinetic behaviors corresponding to complex and prominent phase transitions are still perplexing. Here, we investigate the detailed electrochemical kinetic characteristics of the NaNi1/3Fe1/3Mn1/3O2 electrode by electrochemical impedance spectroscopy (EIS) in three-electrode configurations assistance with the distribution of relaxation times (DRT) and trusted equivalent circuit models numerical analysis. The complex and prominent phase transformations evolution of O3-P3-O3' in the charge process and O3'-P3'-O3 during the discharge process are reflected at different degrees of frequencies and potentials, and significant contributions for the charge transfer step are established on this basis. As the charge and discharge proceed, the influence on charge transfer process by phase transform will be weak, however, which still has some expression and can be caught by EIS assistance with DRT. Additionally, a diagrammatic model for Na+ extraction/insertion is established to illustrate the physicochemical reaction mechanism in the NaNi1/3Fe1/3Mn1/3O2 electrode. The results definitely provide certain scientific thoughts and guiding principles for the commercialization of NaxTMO2 in SIBs.

A homogeneous atmospheric pressure air plasma in a 10 mm gap based on a three-electrode configuration

Generation of atmospheric pressure homogeneous air plasma in a large gap (> 4 mm) is a challenge. In this study, an atmospheric pressure homogeneous air plasma generated in a gap up to 10 mm is reported, which is based on a three-electrode configuration, where a high-voltage (HV) electrode and a middle electrode form a surface dielectric barrier discharge (S-DBD), and together with the ground electrode form the main volume discharge. High-speed photographs confirm that the discharge in the main gap is homogeneous. The gas temperature of the plasma estimated from the N2(C3∏u-B3∏g) (Δv = −2) emission is about 320 K, which is close to room temperature. A detailed analysis shows that the discharge ignited between the HV electrode and the middle electrode is serving as an electron source, and the electrons deposited on the dielectric plate are due to the S-DBD along with the applied voltage generating a driving force, which results in a high concentration of seed electrons in the main gap and induces the homogeneous plasma. Further analysis shows that the electric field in the main gap is only about 18.45 kV·cm−1, which is much lower than the typical breakdown electric field of 30 kV·cm−1 for atmospheric pressure air discharge.

Polynaphthalene-Based Oxazaborinine Complexes Formulated as Red Light Emitters and High-Performance Asymmetric Supercapacitors.

Developing a solid organic emitter based on an oxazaborinine complex with improved photophysical characteristics has become essential to fulfilling the rising need for optical and electrochemical technology. Two oxazaborinine complexes (TNB (a tri-naphthalene boron complex) and DNB (a di-naphthalene boron complex)) decorated with naphthalene and triphenylamine have been developed, which show emission in the red light region in the solid phase. Their effectiveness as asymmetric supercapacitor electrodes in aqueous electrolytes is also being studied. Polynapthaldimine-substituted DNI (di-naphthalene imine) and TNI (tri-naphthalene imine) have been initially synthesized and converted to a N,O-linked boron complex. TNB in solids (λem 660 nm) and the polydimethylsiloxane (PDMS) composite (λem 632 nm) emit pure red light. The optimized structure has been generated, and the HOMO-LUMO energy was calculated with the help of density functional theory (DFT). Due to the higher conjugation effect and lower HOMO-LUMO energy difference, TNB could be used as a supercapacitor electrode. In a three-electrode configuration, TNB has a maximum specific capacitance of 896.25 F/g. Furthermore, an asymmetric supercapacitor device (ASC) was fabricated in an aqueous electrolyte using TNB as a positive electrode having a high specific capacitance of 155 F/g. Even in an aqueous electrolyte, the ASC device reached the operating potential window of 0 to 1.4 V with an enhanced energy density of 42.19 W h/kg and ∼96% cyclic stability after 10 000 cycles. The reported oxazaborinine complex and its electrochemical efficiency in aqueous electrolytes make it ideal for supercapacitor applications and directly impact the development of advanced electrodes for next-generation supercapacitors.

High-performance asymmetric supercapacitors utilizing manganese oxide nanoparticles grafted graphitic carbon nitride nanosheets as the cathode and hypercross-linked polymer derived activated carbon as the anode

Herein, we demonstrated the inexpensive construction of a high-performance asymmetric supercapacitor (ASC) that was combined with manganese oxide nanoparticles grafted graphitic carbon nitride nanosheets (Mn3O4@GCN-NS) as the cathode and nitrogen doped hypercross-linked polymer derived activated carbon (NHCP-AC) as the anode with 6.0 M aqueous KOH electrolyte. In the beginning, Mn3O4@GCN-NS was successfully prepared via a single-step pyrolysis assisted method and the NHCP-AC was synthesized via Friedel-Crafts reaction. The as-synthesized nanocomposites exhibited higher specific capacitance of 436.2 at 0.5 A g−1 in three-electrode cell configuration. Furthermore, the ASC device was fabricated by integrating Mn3O4@GCN-NS with NHCP-AC, which demonstrated considerable energy density of 22.2 Wh/kg at 400 W/kg power density together with remarkable cyclability (93.5 % capacitive retention even after 5000 cycles of charge and discharge). The light emitting diode (5 mm dia.) was powered for about 15 min using two ASC devices coupled in series, demonstrating the effectiveness of its power source. Thus, the results demonstrated that the ASC devices have enormous potential for investigating cutting-edge applications in the field of advanced energy storage.

Facile Synthesis of Pineapple Waste-Derived Carbon and Polyaniline Composite for High-Energy-Density Asymmetric Supercapacitors

Pineapple peel has been chosen as a biowaste precursor to synthesize activated carbon via KOH activation at 800 °C (PP-800). Further, the in situ chemical oxidation method was used to synthesize a composite of PP-800 with polyaniline (PANI). The successful formation of the composite (PP-800/PANI) was confirmed via X-ray diffraction (XRD), and Raman and Fourier-transform infrared (FTIR) spectra. PP-800/PANI when tested in 1 M H2SO4 in a three-electrode configuration showed a higher specific capacitance (377 F/g) than that of PP-800 (328 F/g) and PANI (92.4 F/g) at 2 A/g. This is due to the significant enhancement in the diffusion contribution for PP-800/PANI (86.25%) than that of PP-800 (61.7%) and PANI (49.9%) counterparts at 20 mV/s, which leads to the maximum utilization of the electrochemical surface area. Further, an asymmetrical supercapacitor device, PP-800/PANI//PP-800, was fabricated, which delivered a high energy density of 51.2 Wh/kg at a decent power density of 380 W/kg with 90% cyclic stability after 10,000 charge–discharge cycles.

Additive Manufacturing Sensor for Stress Biomarker Detection

This work presents a new additive manufacturing electrochemical device with conductive graphene and polylactic acid (PLA) filament and its application for epinephrine sensing. A three-electrode configuration based on a screen-printed electrode architecture and an easy-to-connect connector was designed. The sensor surface was chemically treated with dimethylformamide (DMF) to remove the insulating thermoplastic and expose the graphene binding groups. The scanning electron microscopy (SEM) results showed that the surface PLA was removed and the graphene nanofibers exposed, which corroborated the X-ray diffraction spectra (XRD). As a proof of concept, the G-PLA electrode was applied for the determination of epinephrine in human blood samples by square wave voltammetry with a linear range from 4.0 to 100 µmol L−1 and a limit of detection of 0.2 µmol L−1. Based on the results obtained and sensor application, 3D-printed G-PLA proved an excellent choice for epinephrine sensing purposes.

Facile Synthesis of Functionalized Porous Carbon by Direct Pyrolysis of Anacardium occidentale Nut-Skin Waste and Its Utilization towards Supercapacitors.

Preparing electrode materials plays an essential role in the fabrication of high-performance supercapacitors. In general, heteroatom doping in carbon-based electrode materials enhances the electrochemical properties. Herein, nitrogen, oxygen, and sulfur co-doped porous carbon (PC) materials were prepared by direct pyrolysis of Anacardium occidentale (AO) nut-skin waste for high-performance supercapacitor applications. The as-prepared AO-PC material possessed interconnected micropore/mesopore structures and exhibited a high specific surface area of 615 m2 g-1. The Raman spectrum revealed a moderate degree of graphitization of AO-PC materials. These superior properties of the as-prepared AO-PC material help to deliver high specific capacitance. After fabricating the working electrode, the electrochemical performances including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements were conducted in 1 M H2SO4 aqueous solution using a three-electrode configuration for supercapacitor applications. The AO-PC material delivered a high specific capacitance of 193 F g-1 at a current density of 0.5 A g-1. The AO-PC material demonstrated <97% capacitance retention even after 10,000 cycles of charge-discharge at the current density of 5 A g-1. All the above outcomes confirmed that the as-prepared AO-PC from AO nut-skin waste via simple pyrolysis is an ideal electrode material for fabricating high-performance supercapacitors. Moreover, this work provides a cost-effective and environmentally friendly strategy for adding value to biomass waste by a simple pyrolysis route.

Synthesis of hydrothermally derived boron and sulfur-incorporated reduced graphene oxide sheets for supercapacitor applications

The combination of boron and sulfur incorporated reduced graphene oxide (B/S-rGO) was synthesized by a simple hydrothermal technique using a novel and single source of thiophene-2 boronic acid pinacol ester. Structural and functional groups of the synthesized materials were analyzed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis. The Raman analysis revealed the defective structure after incorporating sulfur and boron elements into rGO. The morphological and the presence of elements in the synthesized material were analyzed by scanning electron microscopy, transmission electron microscopy and elemental mapping analysis. The chemical states and chemical composition of B/S-rGO were observed by X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical performance of the prepared material was studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance analysis. GCD studies were performed for B/S-rGO electrode material in an aqueous 1 M H2SO4 electrolyte. The prepared material showed a high specific capacitance of 345 Fg−1 at 1 Ag−1 in a three-electrode configuration. B/S-rGO based device exhibited 97 Fg−1 of specific capacitance at 1 Ag−1 in a symmetric two-electrode configuration. B/S-rGO based symmetric device showed a high energy density of 13.4 Whkg−1 at 249 Wkg−1 and more than 96% capacity retention after 5000 cycles.

Tunnel Junction Engineered Photocarrier Dynamics in Epitaxial Semiconductor Nanowires for Efficient and Ultrafast Photoelectrochemical Photodetectors

Photodetection using photoelectrochemical (PEC) principles is an emerging field in photonics. In recent years, using epitaxial III-nitride nanowires as photoelectrodes, high-performance PEC-type photodetectors (PDs) have been demonstrated, making the epitaxial III-nitride nanowires a scalable, high-performance PEC-PD architecture. Despite the progress, the photodetection performance improvement mainly occurs through incorporating photocatalysts into the nanowire photoelectrodes. In this study, we show that a semiconductor tunnel junction (TJ), which can be a natural component in the epitaxy process of semiconductor nanowires, can drastically improve the photodetection performance of such nanowire-based PEC-PDs. By using a three-electrode PEC cell configuration, we clearly show that an n++-GaN/InGaN/p++-GaN TJ can lead to a factor of 9× improvement on the responsivity of the InGaN nanowire photoelectrode in the blue band due to the TJ-induced photocarrier dynamics tuning, compared to the InGaN nanowire photoelectrode without the TJ. More drastically, the TJ also improves the photoresponse speed of the nanowire photoelectrode by 2 orders of magnitude, and for the electrode with the TJ an ultrafast response time of less than 10 ms is estimated. This TJ concept can also be applied to other TJ structures for other band photodetections. This study therefore sheds new light on further improving the performance of emerging epitaxial nanowire-based PEC-PDs for a wide range of applications from sensing to information processing.

Fabrication of CuCo2S4 on composite interface materials made of polypyrrole and nitrogen-doped carbon nanotubes for use in supercapacitors

Due to their low cost, high conductivity, and synergistic impact, the ternary CuCo2S4 sulfides were thoroughly examined in this article as electrode materials for electrochemical properties. The hydrothermal reaction process for energy storage application was aided by the nanostructured copper cobalt sulfides (CuCo2S4) secured on multiwalled carbon nanotubes/polypyrrole composite via ultrasonication. By utilizing a 6 M KOH electrolyte, the produced composite electrode displays increased specific capacitances and cyclic stability. The structural, morphological, and surface properties of the composite materials were analyzed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDS), X-ray photo electron spectroscopy (XPS), Field emission scanning electron microscopy (FE-SEM), the Brunauer-Emmett-Teller (BET) theory, and the Barrett, Joyner, For better supercapacitor use, the morphological characteristics of nanoscale CuCo2S4 on NMWCNT/PPy surface were confirmed. The synthesized CuCo2S4@NMWCNT and CuCo2S4@NMWCNT/PPy composite electrodes shown outstanding cyclic stability up to 5000 cycles and specific capacitances of 259 F/g, respectively, at 1 A/g. The synthesized ternary composite electrode's electrochemical impedance spectroscopy (EIS) characteristics reveal the lowest Rs (0.53 and 0.63) and charge transfer resistance (Rct) as 65.6 Ω, as well as reasonably outstanding retention of 90.5 % after 5000 cycles. Through the use of a three-electrode configuration, the increased surface and morphological features of the CuCo2S4 on NMWCNT/PPy composite boosted the electrochemical properties of the ternary composite electrode.

ProDOT-Based Polymers: From Energy Storage to Smart Window Applications

Nowadays, electroactive materials based on conjugated polymers for energy storage and electrochromic window applications attract large interest due to their low cost, accessible synthetic procedures, and interesting electrochemical properties. Herein, we report on the performance of two propylenedioxythiophene (ProDOT)-based polymers having varying length and functionality side chains, which were explored to assess their potential for these applications. The polymers were obtained by oxidative chemical polymerization and processed from organic solvents into thin coatings with different molecular assemblies. Preliminary studies on their chemical structure and optical and electrochemical characteristics were performed to evidence how these are influenced by the side chain substituent nature. When tested as electrode material in the three-electrode cell configuration, the synthesized ProDOT-based polymers provided the highest specific areal capacitance of 1.059 mF/cm2 at a scan rate of 10 mV/s and 0.538 mF/cm2 at 0.01 mA/cm2 in cyclic voltammetry and galvanostatic charge–discharge measurements, respectively. One of the polymers showed electrochromic response, with ultrafast color change from deep purple to highly transmissive green/blue. A coloration efficiency of 123 cm2/C and a maximum CE decay of 9.9% after 100 cycles was achieved for this material, which is also able to efficiently store electrical charge, thus demonstrating potential for use in energy storage smart window applications where the energy level can be estimated by simple visual observation.

Optimized Synthesis of Nanostructured Trimetallic Mn–V–Fe Selenides with Battery-Type Behavior for High-Performance Hybrid Supercapacitors

The design and synthesis of innovative materials with a specific architecture are necessary to advance the supercapacitor industry. Recently, transition metal selenides have been identified as an auspicious type of material for energy storage devices due to their enormous electronic conductivity and high theoretical capacitance. Consequently, mono- and diselenides have been extensively investigated. Trimetallic selenides, however, are infrequently reported, and their charge storage mechanism is still not fully understood. Herein, earth-abundant trimetallic Mn–V–Fe selenide (MVF-Se) is successfully fabricated via a two-step hydrothermal approach. The chemical composition, structure, and morphology of the as-synthesized material have been thoroughly characterized. The electrochemical tests revealed that the MVF-Se electrode possesses a high areal capacitance of 16,212.88 mF cm–2 at 1 mA cm–2 in the three-electrode configuration. In addition, the assembled asymmetric supercapacitor device by coupling MVF-Se and activated carbon as the positive and negative electrodes, respectively, demonstrates a desirable 0.56 mWh cm–2 energy density at a 1.0 mW cm–2 power density. After 17,000 charge/discharge cycles, the device exhibits robust cyclic stability with a 95% capacitance retention.

Optimization of Nanocomposite Films Based on Polyimide–MWCNTs towards Energy Storage Applications

In order to obtain polyimide-based composite materials for energy storage applications, four synthetic methods towards a polyimide matrix with 2 wt.% pristine or acid-functionalized MWCNTs have been developed. The polyimide is derived from a nitrile aromatic diamine and a fluorene-containing dianhydride which allowed the formation of flexible free-standing nanocomposite films. The films were thoroughly characterized by means of structural identification, morphology, mechanical, thermal and dielectric behavior, as well as the charge storage performance. The obtained data indicated higher homogeneity of the composites loaded with acid-functionalized MWCNTs that enabled significantly increased dielectric properties compared to the matrix. To assess the electrical charge storage capability, cyclic voltammetry and galvanostatic charge–discharge measurements were employed in a three-electrode cell configuration. Due to the higher conductivity of pristine MWCNTs compared to acid-functionalized ones, increased capability to store charges was achieved by the nanocomposites containing these fillers, despite their lower homogeneity. An attempt to increase the carbonaceous material content was made by applying a thin carbon layer onto the nanocomposite film surface, which led to higher capacitance.

Sustainable Upcycling of Nitrogen-Enriched Polybenzoxazine Thermosets into Nitrogen-Doped Carbon Materials for Contriving High-Performance Supercapacitors

Nitrogen-enriched polybenzoxazine thermosets derived from the ring-opening polymerization of side-chain-type benzoxazine-functionalized polyethylenimine resins (Bz-pei) have been previously reported by our group. In view of the appreciable nitrogen content and significant char yield, these thermosets have been envisioned as enticing carbon precursors and therefore have been sustainably upcycled to nitrogen-doped carbon materials. It is worth mentioning that the sustainable upcycling method should circumscribe energy as well as cost consumption, due to which carbon materials in the present work have been developed under moderate carbonization conditions, without chemical activation treatment. The developed nitrogen-doped carbon materials have been characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, elemental analysis, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The pore topography has been analyzed using scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) analysis has been performed, while the Brunauer–Emmett–Teller (BET) surface area has been determined using nitrogen adsorption–desorption experiments. A comparison of the results obtained from electrochemical investigations performed in a three-electrode setup shows that carbon material upcycled from the guaiacol-based polybenzoxazine thermoset, exhibiting 6.4% nitrogen doping in the carbon framework (labeled as C-GP81), exhibits an impressive capacitance of 700 F g–1 at 10 A g–1 current density, suggesting excellent efficiency and rate capability of the obtained N-doped carbon-material-based supercapacitor electrodes. Furthermore, the carbon material designated as C-GP81 could deliver a maximum energy density (Ed) of 48 Wh kg–1 at a power density (Pd) of 8400 W kg–1 in a three-electrode configuration. The performance of the crafted supercapacitor device for the present study has surpassed the performance reported for polybenzoxazine-derived carbons. Additionally, the performance of carbon material labeled as C-GP81 has been evaluated for its potential as an active component in the electrodes of a symmetric device.

Enhanced Cyclic Stability of Cobalt Doped Bi25FeO40/BiFeO3 as an Electrode Material for a Super Long Life Symmetric Supercapacitor Device

BiFeO3/Bi25FeO40 and cobalt doped Bi25FeO40/BiFeO3 are synthesized by a cost-efficient hydrothermal technique. Cobalt is doped at four different concentrations of 1.5, 2.5, 3.5, and 4.5 mmol in a bismuth ferrite composite (BFCO1, BFCO2, BFCO3, and BFCO4). The capacitive behavior of BFCO3 is significantly higher than those of BFO, BFCO1, BFCO2, and BFCO4 based on their structure, morphology, and electrochemical properties. XRD confirmed the formation of a rhombohedral structure of BiFeO3 and cubic crystal structure of Bi25FeO40 and cobalt doped Bi25FeO40/BiFeO3 composites. Raman modes confirm the presence of cobalt doped Bi25FeO40/BiFeO3 in BFCO3. Microsized particles of BFCO1 were broken upon increasing the concentration of cobalt ion in BFCO2, BFCO3, and BFCO4. In BFCO3, the length of the needle is 0.45 μm and breadth is 0.06 μm, which spread over the spherical-shaped particles with an average size of 0.43 μm. The surface area and average pore diameter of BFCO3 are 60.25 m2/g and 3.38 nm, which are relatively higher than the surface area and average pore diameter of BFO, BFCO1, BFCO2, and BFCO4. The capacitive behavior of BFCO3 shows a significantly higher specific capacitance of 605.16 F g–1 at a current density of 1 A g–1 under 3 M KOH as electrolyte in a three-electrode configuration. The symmetric device of BFCO3 exhibits higher specific capacitance of 176.87 F g–1, specific energy of 35.36 Wh kg–1, and specific power of 1199.43 W kg–1 at a current density of 0.5 A g–1 with super long cyclic stability of about 87% capacity retention, and the coulombic efficiency is about 96% even after 10,000 cycles.

Tailoring the interface magnetron sputtered silver/tungsten disulfide for battery-supercapacitor hybrids: Electrochemical assessment of redox activity

The emergence of two-dimensional transition metal dichalcogenides as a promising material has attracted significant interest in its potential applications. Also, there is a dire need to explore binder-free routes to fabricate electrodes for enhanced energy storage performance. In this study, tungsten disulfide (WS2) films of varying thicknesses were magnetron sputtered onto nickel foam with silver serving as an interface layer for use in a variety of energy storage applications. Using atomic force microscopy, Raman spectroscopy, X-ray diffraction, and the surface and structural characteristics are explored. The Ag/WS2 electrodes were initially evaluated electrochemically in a standard three-electrode cell configuration to identify the best performing sample. By combining the most superior electrode with activated carbon (AC), a hybrid supercapacitor device (Ag/WS2//AC) was assembled. A maximum energy density of 56.5 Wh kg−1 and 4000 W kg−1 power density was displayed by the hybrid device, with remarkable long-term cyclic stability. Calculating the ‘k’ regression coefficients and separating the capacitive-diffusive current contribution were accomplished using Dunn's model. The superior outcomes of Ag/WS2 may enable their integration into advance energy storage devices of the future.

A two-pronged strategy to modulate the porosity of porous carbons for capacitors: The relative effects of the texture and fuel properties of carbonaceous matter

Based on the search for a novel method to modulate the texture properties of porous carbon, it is essential to demonstrate the relative influence of texture and fuel properties (i.e., the general term of volatile, fixed carbon, ash, elements, and calorific value) of carbonaceous matter. Herein, H3PO4 activation was applied to fabricate pine sawdust-derived porous carbons (PC-T; T can be 450, 500, 550, and 600) with various fuel and texture properties. Afterward, the pore architectures recorded for PC-T were adjusted using the CO2 activation procedure; that is, PC-T-derived porous carbons (PC-TC) were obtained. PC-TC showed a significant increase in texture properties (e.g., specific surface area and total pore volume) and specific capacitance compared to PC-T. In the three-electrode configuration, PC-550C achieved high specific capacitance values (e.g., 230.78 F/g at 0.5 A/g). The assembled PC-550C-based symmetrical supercapacitor achieved an impressive specific capacitance of 172.12 F/g upon 0.5 A/g. Interestingly, it equally delivered high energy density (23.91 Wh kg−1) and power density (47.30 kW kg−1), respectively. Further, the specific surface area of the PC-TC samples depends not only on the fuel properties of the PC-T samples but also on the texture properties of the PC-T samples. Superior fabricability and variable texture properties enable the two-pronged strategy (i.e., sequential H3PO4–CO2 activation) for producing bulk senior and multi-level porous carbons.