High Specific Capacitance Value Research Articles

Novel Ball-Type Phthalocyanines with Eight Benzotriazole Groups: Synthesis, Computational DFT Studies, and Supercapacitor Properties

Abstract Novel four MBTOB-bridged ball-type metallophthalocyanines were obtained from 4, 4'-((methylenebis(6-(2H-benzo[d][1, 2, 3]triazol-2-yl)-4-(2, 4, 4-trimethylpentan-2-yl)-2, 1-phenylene))bis(oxy))diphthalonitrile by means of transition metal (II) acetate salts in 2-dimethylaminoethanol. The new starting bisphthalonitrile compound was accomplished from 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol] and 4-nitrophthalonitrile in dimethylformamide under the catalysis of potassium carbonate at 50○C. The structural characterization of the compounds was accomplished by infrared, proton-nuclear magnetic resonance, matrix-assisted laser desorption/ionisation time-of-flight mass, and ultraviolet–visible spectroscopic methods. The supercapacitor performances of the electrodes were examined by cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy analyses. The specific capacitances obtained from the GCD measurements were calculated as 320.4 ± 15.1 F/g for ball-type zinc (II) phthalocyanine in three electrode systems. The highest specific capacitance value was found in the electrode containing ball-type nickel (II) phthalocyanine as 929.8 ± 32.8 F/g at a scan rate of 100 mV/s. In symmetric supercapacitor measurements, the capacitance retention value was 100.7% after 5000 cycles.

Tuning Supercapacitive Behavior of Eri Silk (Philosamiaricini)‐Polyanilne Nanocomposite for Electrodes Applications

ABSTRACTHerein, the synthesis of Polyaniline‐Eri nanosilk fibroin (PANI/ENSF) composite supercapacitor electrode material by utilizing Eri silk (Philosamiaricini) as a raw material and polyaniline (PANI) with H2SO4 as doping acid and (NH4)2S2O8 as an oxidant, via a simple in situ oxidative polymerization technique, with good performance characteristics is reported. The chemical composition of the composites have been studied by using XRD, FT‐IR, UV–vis spectroscopy, Raman spectroscopy, and morphology is studied by SEM. BET analysis reveals that the surface area of composite is 712.10 m2g−1, and BJH analysis shows that the pore size is mainly concentrated between 1.5 and 15.7 nm. The composite shows electrical conductivity of 17.33 × 10−2 Scm−1 (Keithley Model 2000). The electrochemical performances are evaluated by using CV, GCD, and EIS measurements. The three‐electrode system composite shows specific capacitance of about 310.12 Fg−1 at 0.1 Ag−1, which is the highest value being reported, compared to already available polyaniline‐silk composites. Further the studies have been extended to assemble a symmetrical two‐electrode supercapacitor device which also exhibits a high value of specific capacitance of 35 Fg−1 at 5 Ag−1 and 96.12% capacity retention over 5000 cycles. For the first time, this study reports using a Polyaniline‐Eri nanosilk composite to design an efficient supercapacitor electrode.

Graphene, graphene oxide or modified graphene in polyaniline based nanocomposites—features and technical highlights

Polyaniline is a remarkable conjugated polymer having valuable structural and physical characteristics. Nevertheless, polyaniline has poor solubility and structural durability which had limited its practical utilization. Consequently, polyaniline has been reinforced with carbonaceous and inorganic nanoparticles to enhance its processability and physical properties, such as electrical/thermal conductivity and thermal/mechanical stability. Accordingly, polyaniline has been applied as a valuable matrix material to form nanocomposites with graphene which is a one atom thick nanosheet of hexagonally arranged carbon atoms. Subsequently, graphene as well as modified graphene forms have been utilized as important nanoadditives for the polyaniline matrix. This state-of-the-art review article has been designed to investigate the fabrication, characteristics, and applications of the polyaniline and graphene/modified graphene based nanomaterials. Potential enhancements in the physical characteristics of the pristine polyaniline upon graphene reinforcement seemed to be reliant upon the matrix-nanofiller interactions, interface formation, and synergetic effects between polyaniline-graphene. Subsequently, practical aspects of the polyaniline/graphene nanocomposites have been discussed regarding their applications in the fields of solar cells, supercapacitors, and sensors. According to the literature analysis, dye sensitized solar cell based on polyaniline/graphene and polyaniline/graphene oxide exhibited superior power conversion efficiencies ∼2.0-7.6 % and open circuit voltage ∼500-800 mV. Supercapacitor electrodes based on polyaniline/graphene oxide and polyaniline/reduced graphene oxide showed significantly high values of specific capacitance and capacitance retention of ∼1100-1900 Fg−1 and ∼80-98 %, respectively, during >5000-6000 cycles. Besides, the polyaniline/graphene oxide depicted superior sensitivity and response time for gas sensors (∼20 % and 50 s, respectively) and humidity sensors (>90 % and 4-7 s, respectively) and low detection limits for biosensors.

Effect of Cu substitution on morphological optical and electrochemical properties of Co3O4 nanoparticles by co-precipitation method

In this present study, pure Co3O4 and Cu-substituted Co3O4 nanoparticles (NPs) were prepared by a simple co-precipitation method and their structural, morphological, optical, and electrochemical aspects were assessed. X-ray diffraction (XRD) analysis indicated that the synthesized samples had a cubic structure with the formation of a secondary phase (CuO) at a higher Cu concentration. The average crystallite was decreased with increasing Cu content. Fourier transform infra-red (FT-IR) analysis revealed that the presence of vibrational bands in Cu-substituted Co3O4 NPs. The morphological study of the pure Co3O4 and Cu-substituted Co3O4 NPs revealed that the hexagonal structure with porous nature confirmed by Field emission scanning electron microscopy (FESEM). High resolution transmission electron microscope (HR-TEM) analysis with spotty diffraction rings showed that pure Co3O4 and Cu-substituted Co3O4 NPs were polycrystalline in nature. The optical properties of synthesized samples exhibited strong absorption edges, and bandgap values were found to be increased from 3.24 to 3.75 eV. Cyclic voltammetry (CV) was employed to investigate the electrochemical properties of the synthesized materials. The CV curves exhibited pseudocapacitive behavior, and the 2 % Cu-Co3O4 electrode had a high higher specific capacitance value than the pure Co3O4 electrode.

Physical and electrochemical performances of novel tellurium composite films as anode applications in energy storage systems

Portable electronic devices and electric cars use lithium-ion batteries, but clumping lithium alloys limit their lifespan. Due to their strong electronic conductivity, volumetric capacity, and high energy density, researchers are conducting research on electrochemical metal cells utilizing tellurium for high-performance batteries. Theoretically, lithium-tellurium batteries can improve energy densities three times more than lithium-ion batteries. However, metal-tellurium faces challenges such as low rate capability, unclear redox reactions, intermediate dissolution, and electrode volume changes. This study explores the enhancement of the energy storage capacity of next-generation batteries by fabricating coated electrode films as novel anodes from tellurium, silicon, and graphene. Physical, thermal, and morphological analysis of composite material are investigated by XRD, TEM, TGA, DSC, SEM, UV, and XPS analyses, revealing its rigidity as well as durability through its crystal structure alignment and thermal stability. In electrochemical analysis (CV) at various scan rates, samples that exhibit consistent and high specific capacity (Cp) values at different scan speeds (25, 50, and 100 mV/s) indicate excellent ability to store and maintain charge. Decreasing Cp values with increasing scan rates indicate that the speed of cycling limits the charge transfer kinetics and electrode performance. In EIS, the charge transfer resistances (Rct) for the pure Te, Te + Gr, Te + Si + Gr, and Te + Si samples are 759.07 Ω, 4.21 Ω, 36.39 Ω, and 164.90 Ω, respectively. The Te + Gr sample has the lowest Rct, indicating the best charge transfer efficiency at the electrode contact, whereas the Te + Si + Gr sample has a comparatively lower Rct, indicating better charge transfer kinetics. The combined result exhibits the synergistic impact of tellurium, silicon, and graphene in enhancing the energy storage capacity of future batteries across the industry.

Attaining promising efficiency through a Quasi-Solid-State symmetrical supercapacitor and Dye-Sensitized solar cell counter electrode utilizing bifunctional Nitrogen-Doped microporous activated carbon

This study addresses the imperative need for high-performance and sustainable energy storage and conversion technologies by leveraging the unique properties of nitrogen-doped porous carbon (N@WnAC) derived from the waste walnut shells (WnS). In the realm of supercapacitors, the N@WnAC demonstrates remarkable performance in a three-electrode system, showcasing a high specific capacitance value of 276.7 Fg−1 at 1 Ag−1, outstanding stability (96.6 %, 5000 charge–discharge cycles) and favourable rate capability (68.8 % at 10 Ag−1). Moreover, a quasi-solid-state symmetrical supercapacitor (N@WnAC//N@WnAC) is fabricated with PVA/H2SO4 gel electrolyte, underscores outstanding performance by delivering high capacitance (126.2 Fg−1 at 0.5 Ag−1), promising rate capability (71.8 % at 5 Ag−1), favourable long-term stability (93.3 %, 5000 charge–discharge cycles), and faster charge–discharge kinetics compared to conventional counterparts. At the same time, N@WnAC//N@WnAC delivers a high energy density (42.27 Whkg−1 at 0.5 Ag−1) that was retained up to 23.96 Whkg−1 even at 5 Ag−1. Simultaneously, the study explores the potential of N@WnAC as a counter-electrode (CE) in dye-sensitized solar cells (DSSC). The obtained results underscore that unique nitrogen doping enhances the electrocatalytic activity, leading to improved electron transfer kinetics and overall cell performance. Moreover, the N@WnAC CE-based DSSC delivers a promising overall solar-to-electrical conversion efficiency of 5.84 %.

Bimetallic ions modified 2‐methylimidazolium functionalized polypyrrole/graphene oxide for the improved supercapacitor

AbstractThin films with two‐dimensional (2D) nanostructures possess good environmental stability, thinner thickness and large surface area, which are widely used as a promising modified electrode material in the field of energy storage, supercapacitors, electrochemical sensors and biosensors. Herein, unique bimetallic ions modified polypyrrole/graphene oxide (PPy/GO) nanosheets, including Co2+‐Zr4+/(2‐MeIm)x@PPy/GO and Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4), are prepared by using 2‐methylimidazolium (2‐MeIm) as the linkers between PPy/GO and metal ions. The obtained electrodes constructed by Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4) and Co2+‐Zr4+/(2‐MeIm)x@PPy/GO exhibit improved capacitor electrochemical properties due to the reversible redox reaction, the large specific surface area and the high theoretical specific capacitance value of the metal ions compared to the unmodified PPy/GO. Especially, the specific capacitance value of Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4) electrode reaches 321.78 F g−1 at a current density of 1 A g−1 and the capacitance retention rate is achieved to 100% in the long cycle charge/discharge test after 10 000 cycles (10 A g−1). It will provide a practical experience for the design and preparation of supercapacitors based on bimetallic ions modified PPy/GO.

Co-precipitation Synthesis and Characterization Studies of Manganese Oxide Doped with Nickel for High-Performance Energy Storage Supercapacitor Application

The advancement in nanotechnology research has facilitated the development of eco-friendly methods for the synthesis of nanoparticles. In this work, nickel (Ni)-doped manganese oxide was synthesized using the co-precipitation method. The prepared Ni-doped manganese oxide products have been characterized by X-ray powder diffraction, scanning electron microscopy (SEM), transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS). The preliminary electrochemical characteristics include charge-discharge cycling, which improves the conductivity and capacitance of the high-performance aqueous asymmetrical supercapacitor. The CV analysis of the Ni-doped manganese oxide electrode demonstrated a distinctive pseudocapacitive behavior in 1 M KOH solution. The nickel (Ni) doped electrode has a higher specific capacitance value than the pure manganese oxide electrode, with a value of 2225.07 F×g-1 at a scan rate of 5 mV×s-1. Keywords: Supercapacitor, Co-precipitation method, Nanotechnology, Synthesized, Electrochemical

WO3 Nanoparticle/Biomass Derived N‐Doped Activated Carbon Decorated with Polyaniline Nanofibers Ternary Nanocomposite for High‐Performance Symmetric and Asymmetric Supercapacitor

AbstractSupercapacitors have captured the curiosity of researchers due to their extremely high energy storage capacity. Hybrid supercapacitors deliver high specific capacitance values compared to the exciting (electrical double layer capacitor) EDLC and pseudocapacitors. This work presents a simple and scalable synthetic method to design a hybrid ternary composite as electrode material. In this work, the combination of EDLC‐type behaviour material, i. e., sustainable biomass‐derived Nitrogen‐doped activated carbon (NAC) and pseudocapacitive behaviour electrode materials, i. e., metal oxides (tungsten oxide) and conductive polymer (polyaniline) are selected to achieve a high gravimetric capacity. The PANi/WO3/NAC (PWNAC) ternary composite is tested for symmetric and asymmetric supercapacitor (ASC). In a symmetric capacitor, PWNAC acts as both the positive and negative electrode, whereas in ASC, PWNAC acts as the positive electrode and NAC as the negative electrode. It is observed that the ASC shows a better capacitance value than symmetric. ASC operates at a potential range of 1.4 V in 1 M H2SO4 aqueous electrolyte, shows a maximum capacitance of 608.2 F/g at 0.5 A/g, and has long capacitance retention of 98.32 % of its initial capacitance after 2000 charge‐discharge cycles.

Improved Structural and Electrochemical Properties of Mg-Doped Nickel Cobaltite Nanoparticles Synthesized Using Low-Temperature Microwave Hydrothermal Method

The specific capacitance of materials influences the energy storage capacity. A series of MgxNi1-xCo2O4 (x = 0.0 - 0.1) nanoparticles using the low-temperature microwave-hydrothermal (M-H) method at 160 0C temperature, and sintered at 600 °C. The samples were then characterized using X-ray diffraction (XRD), Field Emission Scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). It is observed from X-ray diffraction that all the samples are cubic spinel in nature with space group Fd-3m, and the lattice parameter varies between 8.097 (x = 0.0) and 8.083 (x = 0.10). The nanoparticles have a hexagonal nanoflake-like shape morphology with an average particle size of 180 nm to 350 nm. The tetrahedral and octahedral absorption bands were observed at 561 cm-1 and 654 cm-1, respectively. The valence states of Ni2+/Ni3+, Co2+/Co3+, and Mg2+ were confirmed by X-ray photoelectron spectroscopy. The electrochemical studies using CV and GCD were performed on all the samples. High values of specific capacitance of 332 F g−1, energy densityof 9.05 Wh kg-1, and power density of 224.84 W kg-1 were observed for the sample x = 0.08. Therefore, Mg0.08Ni0.92Co2O4 sintered at 600 °C shows good impedance and electrochemical properties, which are helpful for supercapacitor applications. Figure 1

New Hybrid Materials Based on N-Doping Copolymers of Thiophene Derivatives for Electrochemical Energy Storage

Over the past decade, electroactive conducting polymers (ECPs) are among the most potential pseudocapacitive materials for the electrodes of microsupercapacitors. ECPs exhibit several advantages, such as good conductivity (up to 103 S cm-1), flexibility, high specific capacitance (values ranging from 300 to 800 F.g-1 depending on synthesis and electrochemical performance conditions), relatively cheap and ease of synthesis [4]. Therefore, the electrochemical deposition of ECPs revealed a new strategy to design a great variety of various polymer morphologies as an innovative pseudocapacitive materials. Based on the different storage mechanism, electrochemical supercapacitors can be divided into three types, namely electrochemical double layer capacitors (EDLCs), pseudosupercapacitors and hybrid supercapacitors in which ECPs and other pseudocapacitive materials such as carbon materials, transition metal oxides, nitride complexes allow to store higher amount of capacitance per gram (faradic reactions) than EDLCs (pure capacitive energy storage reaction).In this work, we have elaborated new n-doped conducting polymers Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] by making electropolymerization on Pt disk electrode and 3 nm alumina coated silicon nanowires in acetonitrile organic electrolyte. The comonomers 3,6-bis(thienyl)pyridazine and (3,6-bis(2-(3-nhexylthienyl))pyridazine) have been successively synthesized. The produced polymeric materials Poly[3,6-bis(2-thienyl)pyridazine] and Poly[3,6-bis(2-(3-n-hexylthienyl))pyridazine] during n-doping process on Pt working electrode in acetonitrile solution of TBAPF6 (0.1 M) expose very low potential value of -2.23 V and -2.19 V at current density of -0.25 mA.cm-2 and -0.06 mA.cm-2, respectively. The elctropolymerization of synthesized comonomer 3,6-bis(thienyl)pyridazine has been done on Al2O3@SiNWs and resulted in thin layer of polymer film with micropores. The experimental results are compared to electropolymerization study of thiophene monomer on Pt disk and Al2O3@SiNWs electrodes to highlight the similarities and electrochemical advancements.

Pseudocapacitive Electrode Based on MnO2 Loaded Activated Charcoal on Graphite Paper for Sustainable Energy Storage

AbstractThe design of high‐performance electrode material without compromising energy and power density is critical for the advancement in hybrid electric vehicle technology. In this perspective, we have fabricated a MnO2 loaded activated charcoal‐based electrode on graphite paper as an endeavour to improve the energy storage capabilities. The electrode material is synthesized by employing a sustainable route and the structural, microstructural, and textural properties have been investigated. The electrochemical performance for energy storage is evaluated and the fabricated electrode on graphite paper exhibits remarkably high‐power density (811 W kg−1) maintaining high energy density (106 Wh kg−1) at the same time, along with high gravimetric specific capacitance value of 768 F g−1 at 2 mA cm−2. The obtained results demonstrate the excellent performance of the electrode material, suggesting MnO2 loaded activated charcoal as a prospective electrode material to meet the demand of hybrid electric vehicles as well as to contribute to our transitioning towards low‐to‐zero carbon emission technology.

Self-Assembled MXene Supported on Carbonization-Free Wood for a Symmetrical All-Wood Eco-Supercapacitor.

As an emerging two-dimensional (2D) material, MXene has garnered significant interest in advanced energy storage systems, yet the stackable structure, poor mechanical stability, and lack of moldability limit its large-scale applications. To address this challenge, herein, the self-assembly of MXene on carbonization-free wood was obtained to serve as high-performance electrodes for symmetrical all-wood eco-supercapacitors by a steam-driven self-assembly method. This method can be implemented in a low-temperature environment, significantly simplifying traditional high-temperature annealing processes and generating minimal impact on the environment, human health, and resource consumption. The environmentally friendly steam-driven self-assembly strategy can be further extended into various wood-based electrodes, regardless of the types and structures of wood. As a typical platform electrode, the optimized MXene@delignified balsa wood (MDBW) achieves high areal capacitance and specific capacitance values of 2.99 F cm-2 and 580.55 F g-1 at an extensive mass loading of 5.16 mg cm-2, respectively, with almost loss-free capacitance after 10,000 cycles at 50 mA cm-2. In addition, an all-solid-state symmetrical all-wood eco-supercapacitor was further assembled based on MDBW-20 as both positive and negative electrodes to achieve a high energy density of 19.22 μWh cm-2 at a power density of 0.58 mW cm-2. This work provides an effective strategy to optimize wood-based electrodes for the practical application of biomass eco-supercapacitors.

The incorporation of cobalt ions into hydroxyapatite nanostructure for a novel range of electrochemical energy storage applications

Supercapacitors (SCs) have garnered extensive attention for their notable advantages, including extended cycle life, high energy density, and cost-effectiveness. Due to their large energy storage capacity and high output power, the development of pseudocapacitive materials for energy-oriented applications has been of great importance. The integration of nanoscale active materials in batteries results in faster redox kinetics. Consequently, alters the material's electrochemical characteristics from battery-like to pseudocapacitive-like behavior driven by enhanced surface area and reduced diffusion routes. This study aims to investigate the efficacy of pure hydroxyapatite and Co2+-doped hydroxyapatite (HAP) nanoparticles as electrode materials for SCs. The pure HAP and Co2+-doped HAP nanoparticles were synthesized via the Sol-Gel method. Electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the electrochemical behavior of the developed electrode. The highest values of specific capacitance (Csp) and energy density for the SC with Co2+-doped HAP nanoparticles electrode were obtained at 324 F g−1 and 145.8 Wh kg−1, respectively, at a current density of 1.2 A g−1. According to the data above, Co2+-doped HAP nanoparticles can be used as a substitute to improve electrochemical performance in energy storage applications.

Characterization and antibacterial studies of Sn doped CuO nanocomposite using centratherum punctatum leaf extract

In order to synthesize CuO, SnO2, and Sn doped CuO nanocomposites, accessible and non-toxic materials, specifically leaf extract from Centratherum punctatum, were used in this work to apply the concepts and practices of green chemistry. These methods are both economical and environmentally friendly. A comprehensive range of characterisation techniques, including as FTIR, X-ray diffraction, and UV-vis spectroscopy, were also used to confirm the structures of all the produced nanomaterials. Instead, FESEM and EDAX were used to analyze the morphologies and elemental composition of recently produced nanomaterials. A decline in the optical band gap values was indicated by the red shift observed in the UV-vis study following tin doping. A sample's presence of different functional groups is confirmed by FT-IR analysis. For CuO NPs, SnO2, and Sn doped CuO NCs, the XRD results yielded crystallite sizes of 6 nm, 21 nm, and 29 nm, respectively, for the produced particles. The ferromagnetic, diamagnetic, and super paramagnetic characteristics of the produced samples at room temperature were validated by vibrating sample magnetometer experiments. Cyclic voltammetry is used to examine the nanoparticles' electrochemical analysis. Using Sn doped CuO nanocomposite material, it shows a high specific capacitance value of about ~187 Fg-1 at a current density of 10 mV/s. It was found from the electrochemical studies that the produced nanomaterials are suitable for capacitive behaviour. After all, the presence of inhibition zones surrounding each well led us to the conclusion that the nanoparticles exhibited antibacterial activity against the pathogenic strains of Staphylococcus aureus and Escherichia coli.

Exploring Zinc Vanadate/Cobalt Oxide (Zn3(VO4)2/CoO) Nano Hybrid Composites as Supercapacitors for Sustainable Energy Storage Applications

A hybrid nanocomposite of zinc vanadate/cobalt oxide (Zn3(VO4)2/CoO at ratios of 90/10, 80/20, 50/50, and 20/80) was obtained using a simple co-precipitation technique, then calcinated for 4 hrs at 400°C. The surface morphological, vibrational, and structural characteristics of the synthesized hybrid nanocomposites were examined. According to the structural study, orthorhombic Zn3(VO4)2 and cubic crystal systems of CoO with space groups Fm-3m were formed. The functional groups of Zinc Vanadate/Cobalt Oxide were examined using FTIR spectroscopy. A scanning electron microscopy (SEM) study reveals the nanosheets structures with the size of 200 nm. The chemical composition and formation of the Zn3(VO4)2/CoO composites were confirmed using X-ray photoelectron spectroscopy (XPS). The electrochemical performance of the hybrid nanocomposites was assessed through CV, GCD and impedance analysis. Among the nanocomposites, Zn3(VO4)2/CoO 80/20 exhibited a high specific capacitance value of 564.36 Fg-1 and retaining 97% of their total capacitance even after 3000 cycles.

Effect of electrolytes on supercapacitive behavior of cubic shaped pristine cuprous oxide synthesized via sol-gel approach

The present study uses the sol-gel approach to employ cuprous oxide (Cu2O) as an electrode material for the electrochemical energy storage application. Scanning electron microscopy (SEM) examines the structural and surface morphological characteristics of the synthesized material, and pure phase development is verified by the X-ray Diffraction (XRD) patterns. The synthesized material has a high value of specific capacitance, notable porosity, and a well-defined cubic shape. In the three-electrode set-up, the electrochemical analysis uses different aqueous electrolytes, i.e., KOH and NaOH. The electrochemical outcomes indicate that the synthesized material has a maximum specific capacitance (Cs) of 362.77 Fg-1 with excellent stability (104 %) in 6 M NaOH than KOH electrolyte (225 Fg-1). EIS data for Cu2O-based electrodes have been modeled using various equivalent circuits. The ESR value of Cu2O in NaOH electrolyte is much smaller (0.503 Ω) than in KOH electrolyte, indicating the creation of more active sites and enhanced accessibility of ions. Capacitive and diffusion current contributions are shown by using the Trassati and Dunn techniques. Thus, all our findings suggest that sol-gel synthesized pristine cuprous oxide is a potential option for energy storage gadgets.

Activated Carbon Derived from Cucumber Peel for Use as a Supercapacitor Electrode Material.

Biowaste conversion into activated carbon is a sustainable and inexpensive approach that relieves the pressure on its disposal. Here, we prepared micro-mesoporous activated carbons (ACs) from cucumber peels through carbonization at 600 °C followed by thermal activation at different temperatures. The ACs were tested as supercapacitors for the first time. The carbon activated at 800 °C (ACP-800) showed a high specific capacitance value of 300 F/g at a scan rate of 5 mV/s in the cyclic voltammetry and 331 F/g at the current density of 0.1 A/g in the galvanostatic charge-discharge analysis. At the current density of 1 A/g, the specific discharge capacitance was 286 F/g and retained 100% capacity after 2000 cycles. Their properties were analyzed by scanning electron microscopy, energy-dispersive X-ray analysis, porosity, thermal analysis, and Fourier-transform infrared spectroscopy. The specific surface area of this sample was calculated to be 2333 m2 g-1 using the Brunauer-Emmett-Teller method. The excellent performance of ACP-800 is mainly attributed to its hierarchical porosity, as the mesopores provide connectivity between the micropores and improve the capacitive performance. These electrochemical properties enable this carbon material prepared from cucumber peels to be a potential source for supercapacitor materials.

A DFT-based design of B/N/P-co-doped oxo-triarylmethyl as a robust anode material for magnesium-ion batteries

Magnesium-ion batteries (MIBs) are emerging as a promising alternative to lithium-ion batteries (LIBs) due to their superior safety features and cost-effectiveness. In this work, heteroatoms-co-doped oxo-triarylmethyl (B/N/P@oxTAM) as a favorable anode material for MIBs was investigated using density functional theory calculations. The B/N/P@oxTAM is a highly porous structure and has a better affinity for Mg-ions to attach to vacancy site. Partial density of states, open-circuit voltage, theoretical specific capacity, and diffusion energy barrier were calculated and discussed. A significant decrease in the HOMO-LUMO gap with no structural deformation occurred, suggesting the high cycling performance of B/N/P@oxTAM for MIBs. Moreover, the designed anode material demonstrated full loading with six Mg-ions at different active sites, indicating a high theoretical specific capacity of 513.75 mAh g−1 and a low open-circuit voltage of 0.07 V. The presence of a heterocyclic ring (borabenzene) with a diffusion energy barrier of 0.039 eV increased the diffusion of Mg-ions. Therefore, B/N/P@oxTAM can be used as a viable anode material for MIBs with extended life cycle and quick charge-discharge rates due to its low open-circuit voltage and diffusion energy barrier, as well as its high theoretical specific capacity value.

Intrinsic pseudocapacitive enhancement of NiCo2O4/activated carbon composites for high-performance supercapacitors

The high electrical conductivity and capacitance of NiCo2O4 have made it a promising electrode material for supercapacitors with advantages in rapid energy storage, long cycle life, and potential for flexible applications. Nickel Cobaltite Oxide (NiCo2O4) nanoflakes were successfully synthesized by the sol–gel method. The composite Activated carbon was made from waste coconut shells. The X-Ray Diffraction (XRD) pattern matches with the standard values, the crystallite sizes were found to be 7 nm using the Debye Scherrer formula. FTIR reveals the molecular bond of (NiCo2O4) NFs and their composites peak at 541 cm−1 and 552 cm−1 confirms the formation of NiCo2O4 Metal oxides. From optical absorption studies, it is found that both NiCo2O4 NFS and NiCo2O4/AC composites have maximum absorption throughout the UV region. The bandgap increases from 1.26 eV to 1.34 eV on adding AC composites to NiCo2O4 NFs. Scanning Electron microscopy (SEM) shows the formation of NiCo2O4 nanoflakes. The activated carbon has high surface area with micropores, confirmed by BET analysis. Cyclic Voltammetry (CV) analysis shows that NiCo2O4/AC composite has a more specific capacitance at low scan rate of 10 mV/s, which is more than NiCo2O4 NFs. Both the samples recorded high specific capacitance values of 142 F g−1 and 192 F g−1 at the current density of 1 A/g using GCD. From this NiCo2O4/AC composites may be a high-performing capacitor with intrinsic pseudocapacitive behaviour compared to NiCo2O4 NFs which has extrinsic pseudocapacitive behaviour.