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In the recent years, the whole world is looking for better energy storage devices. Supercapacitors are among the most promising high-capacity energy storage devices. Manganese-based material has gained more importance among transition metals due to its cost, easy fabrication, and wide potential applications. Here, we report the synthesis of a novel MOF using metal centers, dicarboxylate ligand, and aminoterephthalic acid as a co-ligand {Mn-Ni-NH2(h2fipbb)}MOF. The synthesized material has a unique hierarchical morphology consisting of manganese and nickel connected with NH2 through h2fipbb ligand linkage, which is highly efficient for the permeation of the electrolyte and electron transfer. The {Mn-Ni-NH2(h2fipbb)}MOF shows an excellent specific capacitance of 711.60 F g−1 using 2 M KOH at a current density of 1 A g−1. The two electrode system material exhibits a high-power and energy density of 743.99 W kg−1 and 20.49 Wh kg−1, respectively. From the above results, the synthesized {Mn-Ni-NH2(h2fipbb)}MOF can be considered a promising material for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

The carbon nanotubes attached mesoporous Ag3O4-coated NiO nanosheets were prepared successfully through hydrothermal method. The structural, morphological and electrochemical properties of the prepared nanocomposite have been studied. The X-ray diffraction and Raman analysis confirms the presence of NiO, Ag3O4 and carbon nanotubes in the prepared sample. HRTEM images clearly show the coating of Ag3O4 on the NiO and attachment of carbon nanotubes. BET surface area analysis confirms the mesoporous nature of the prepared composite. The cyclic voltammetric (CV), galvanostatic charge-discharge (GCD) and impedance analysis were made to explore the electrochemical nature of the composite. Cyclic voltammograms reveals the maximum specific capacity of 415.86 mAh g−1 at the scan rate of 3 mV s−1 and GCD analysis exhibits the specific capacity of 416.63 mAh g−1 at 1 A g−1. The prepared nanocomposite retained 97% of maximum capacity even after 1500 cycles. [ABSTRACT FROM AUTHOR]

Transition metal oxide-based magnetic nanocomposites attract great attention due to their unique properties and applications in the field of energy storage. Herein, we present a facile microwave procedure for the synthesis of CuFe2O4 (CF) and CuFe2O4 incorporated with reduced graphene oxide CuFe2O4/rGO (CG) as potential electrode materials for hybrid supercapacitor. The structure and morphology of CF and CG nanoparticles are examined. The electrochemical performance is studied in 6 M aqueous KOH electrolyte using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. The attractive CG nanocomposite exhibits high specific capacity of 800 C/g at a current density of 2 A/g and better cycling stability when compared to pure CF, due to the formation of nanostructure composed of ferrite nanoparticles homogeneously incorporated onto rGO sheets. Furthermore, the practicability of CG electrode is investigated by the fabrication of CG and activated carbon. The hybrid supercapacitor device shows excellent electrochemical performance with specific energy of 18.3 Wh/kg and a specific power of 455 W/kg. It is noteworthy that the cyclic stability is excellent with a capacity retention of ~98% after 3000 cycles manifesting the superiority of CG electrode. The proposed device demonstrates the potential to fabricate other metal oxides with activated carbon via a facile synthesis method for promoting application in energy storage materials and promoting new opportunities of binary nanocomposite. [ABSTRACT FROM AUTHOR]

Abstract Synthesis of polyoxometalates (Cu 3 Mo 2 O 9 nanopowders) was obtained by using solvothermal method and confirmed by X-ray diffraction pattern, with orthorhombic crystalline structure belonging to the space group Pna2 1 (33). Further, the synthesized Cu 3 Mo 2 O 9 nanopowders were analyzed by using Raman, infrared, and photoluminescence studies. X-ray photoelectron spectroscopy study explained the oxidation states of Mo-3d, Cu-2p, and O-1s in Cu 3 Mo 2 O 9 nanopowders. Field emission scanning electron microscopy images clearly revealed the formation of nanostructure randomly oriented to form an interconnected rout, which emerged as a good candidate for storing more charges at the surface of Cu 3 Mo 2 O 9 nanopowders. The electrochemical studies, such as cyclic voltammetry, electro impedance analysis, and galvanostatic charging–discharging studies, were used to analyze its electrochemical properties. To ensure the stability of Cu 3 Mo 2 O 9 nanopowders, continuous charging and discharging studies were conducted for 1000 cycles at a current density of 5 A g−1 and it exhibited good stability over a large number of cyclic studies with capacity retention of 99.2% after the first 500 cycles. [ABSTRACT FROM AUTHOR]

Vanadium pentoxide (V2O5) based electrodes for energy storage devices have captured sizeable attention in the past decade owing to their attractive physiochemical features. In the present work, flaky structured V2O5 was prepared using a single step hydrothermal route. The results from analytical investigations hold up well with the formation scheme proposed. The flaky morphology of V2O5 facilitates additional pathways for electron transport and effective ion access. When employed as a supercapacitor electrode in a neutral electrolyte, this flaky V2O5 electrode demonstrates a specific capacitance of 472 F g−1. Besides, it retains maximum capacitance at higher current density confirming its good rate performance. An asymmetric type supercapacitor using flaky V2O5 as positive electrode and activated carbon as negative electrode exhibits specific capacitance of 69 F g−1. This device shows energy density of 10 W h kg−1 within the operational window of 1 V. [ABSTRACT FROM AUTHOR]

NiO/NiSnO3 nanocomposite synthesis was accomplished by a hydrothermal method. The role of polyvinylpyrrolidone and experimental parameters in the configuration of NiO/NiSnO3 nanocomposite was studied by employing standard characterization techniques. Electrochemical properties were demonstrated by adopting cyclic voltammetry, electro-impedance spectra and galvanostatic charging and discharging studies. All the obtained products have contact resistance Rct of 0.72 Ω at low frequency arising from the resistance between the working electrode and the electrolyte. The NiO/NiSnO3 nanocomposite superior properties may arise from nanosized rod morphology due to their inherent properties having a significant impact on their electrochemical properties. The specific capacitance for RSA3 can be estimated as 524 F/g at a current density of 0.5 A/g. [ABSTRACT FROM AUTHOR]

To accomplish superior performance in supercapacitors, a fresh class of electrode materials with advantageous structures is essential. Owing to its rich electrochemical activity, vanadium oxides are considered to be an attractive electrode material for energy storing devices. In this work, vanadium pentoxide (V2O nanostructures were prepared using surfactant (CTAB)-assisted hydrothermal route. Stacked V2O5 sheets enable additional channels for electrolyte ion intercalation. These stacked V2O5 nanosheets show highest specific capacitance of 466Fg at 0.5Ag. In addition, it exhibits good rate capacity, lower value of charge transfer resistance and good stability when used as an electrode material for supercapacitors. Further, an asymmetric supercapacitor device was assembled utilizing the stacked V2O5 sheets and activated carbon as electrodes. The electrochemical features of the device are also discussed. [ABSTRACT FROM AUTHOR]

• Binder-free Star-like 3D-Co 3 O 4 /Ni forest positive electrode was synthesized via hydrothermal process. • Star-like 3D-Co 3 O 4 /Ni electrode exhibits high areal capacity of 143.28 mC cm−2 at 0.5 mA cm−2 with 88.4% retention. • Supercapattery device exhibited an energy density of 6.73 μWh cm−2 at power density of 700 μW cm−2. • 3D forest-like architecture results in better performance due to high surface area and porous nature in foot print area. [Display omitted] A binder-free positive electrode material of 3D starfish-like Co 3 O 4 /Ni forest is fabricated via a novel and facile hydrothermal process followed by thermal treatment. The morphological studies clearly showed the construction of starfish-like micro-flowers of Co 3 O 4 nanostructure forest densely covered on the entire Ni current collector. The 3D-Co 3 O 4 /Ni electrode displayed an areal capacity as high as 143.28 mC cm−2 at 0.5 mA cm−2 and higher stability of 88.4% after 5000 cycles. Moreover, the fabricated 3D-Co 3 O 4 /Ni||3D-Bi 2 O 3 /Ti s upercapattery delivered a maximum areal capacitance of 24.73 mF cm−2, the energy density of 6.73 μWh cm−2 and power density of 5250 μW cm−2 with good cycling stability> 71% capacity retention after 5000 cycles. The higher electrochemical performance of the electrode is delivered due to the availability of abundant electrochemically active sites in the 3D starfish-like Co 3 O 4 microflower, which facilitates a higher electrochemical reaction. The starfish-like forest architectures allow rapid ion diffusion, and the binder-free electrode reduces the contact resistance, which fasten the electron transport. These tolerable results prompt the as-prepared electrode with 3D starfish-like Co 3 O 4 microflower morphology as an auspicious positive electrode material for electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

At present scenario, the design of newer energy storage devices primarily focuses on superior capacity, rate performance, cost-effectiveness and stability. Among the other available Bi-Transition Metal oxides (BTMO's), NiFe 2 O 4 is a favorable material for electrochemical supercapacitor (SC) applications due to the presence of two metal moieties. The strategy of combining carbon-based material with the metal ferrite improves the electrochemical behavior. Herein, we fabricated reduced graphene oxide (rGO) decorated with NiFe 2 O 4 nanoparticles using a commercially available microwave device. The as-prepared NiFe 2 O 4 /rGO (NG) nanocomposite exhibits a high surface area with increased porous nanoparticles that allow fast ion- diffusion which favors the electrochemical activity. Further, we have explored the use of bare and NiFe 2 O 4 /rGO samples for SC electrode application. The NG nanocomposite electrode material exhibits better electrochemical characteristics including a high specific capacity of 1320 Cg−1 at a current density of 1 Ag−1 and long cycle stability with 94% capacitance retention after 5000 cycles when compared to bare NF in alkaline (6 M KOH) electrolyte. In addition, we have assembled NG based full cell SC device using NG and activated carbon (AC) as electrodes. The fabricated SC device shows the high specific capacity and remarkable cyclic stability. It also exhibited an energy density of 75 Whkg−1 at a power density of 2343 Wkg−1 respectively. Hence, the proposed NG electrode material promotes new opportunities for utilizing this composite material as a promising electrode material for future energy storage devices. [Display omitted] • Nickel ferrite/rGO binary nanocomposite and Nickel ferrite nanoparticles prepared using microwave method is proposed. • NG nanocomposite shows high specific capacity of 1320 Cg−1 when compared to that of bare NF. • NG nanocomposite exhibits 94% capacitance retention after 5000 cycles at 4 Ag−1. • The fabricated supercapacitive device l exhibits energy density of 75 Whkg−1 at a power density of 2343 Wkg−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Kaolin/g-C 3 N 4 /WO 3 nanocomposite has been synthesised and characterised. • The ternary nanocomposite has been characterized by various analytical techniques. • The specific surface area of the nanocomposite is obtained using BET isotherm. • The energy storage application of the nanocomposite has been studied using electrochemical, impedance and GCD studies. In order to investigate the synergistic potential of a new nanocomposite for improved energy storage applications, this work combines graphitic carbon nitride (g-C 3 N 4), vanadium pentoxide (V 2 O 5) and kaolin. Kaolin functions as a structural matrix, offering stability and support for the integration of g-C 3 N 4 and V 2 O 5 nanoparticles. It is well-known for its wide availability and thermal characteristics. A variety of analytical methods, such as electrochemical analysis, scanning electron microscopy and X-ray diffraction, are used to characterise the synthesised nanocomposite. The specific capacitance and cycling stability of the nanocomposite's electrochemical performance are rigorously assessed. Key issues in efficiency, stability and cost-effectiveness are addressed by an optimised material for advanced energy storage systems, which is the result of the synergistic effects coming from the unique features of each component. With a superior cyclic stability and capacitance retention of 77.7 % even after 2000 cycles, the composite material exhibits a higher specific capacitance value of 415 Fg−1 at 5 mVs−1. This work is a major step towards the creation of novel nanocomposites for high-performing, environmentally friendly energy storage systems. [ABSTRACT FROM AUTHOR]

Metal selenides of were synthesized for various weight percentage of Mn (0.05, 0.1, and 0.15 wt %). MnSe 2 -CoSe 2 emerged as the novel-energy storing material for the supercapacitor application and guaranteed the improved electrochemical performance in asymmetric configuration. As prepared metal selenide composite was explored for standard characterization studies. XRD reveals the highly crystalline in nature of the as prepared samples. Se bonding with Mn-Co is confirmed from the sharp peak obtained at 470 cm−1. The chemical elemental composition was evaluated by the XPS, hence the characterization outcome confirm the successful growth of the material. The specific capacitance of Mn3 (0.15 wt %) is 373 Fg-1 in 1 M KOH; Mn1 (0.05 wt %-184 Fg-1) and Mn2 (0.1 wt %-295 Fg-1). The electrode shows excellent capacity retention of 95.86% at 5 Ag-1 even after 5000 cycles. Furthermore, asymmetric configuration of Mn3 (0.15 wt %)//AC device delivered significant value of power density even at high energy density. Thus, the as-prepared asymmetric device easily illumines the green light emitting diode which indicates the Mn3 (0.15 wt %) is an acceptable product. [ABSTRACT FROM AUTHOR]

In today's sophisticated world, the need for electric energy is increasing every day. Therefore, it is essential to manufacture electrode materials to store electric energy. Nickel, bismuth, and cobalt vanadium oxides are considered a member of a group of the best anodes in energy storage applications. In this study, three kinds of anode materials were analyzed for their better electrochemical behavior. Hydrothermal method was preferred for all the synthesis processes. The basic characterization studies such as X-ray diffraction, photoluminescence, Raman, and Fourier transform infrared confirmed the presence of nickel, bismuth, and cobalt vanadium oxides. The highest specific capacitance value of 426.11 F/g in cyclic voltammetry and 285.65 F/g in galvanostatic charge–discharge (GCD) measurements was obtained for the cobalt vanadium oxide samples. Furthermore, stability test in GCD showed its 83.64% capacitive retention over 5000 cycles at a high (5 mA/g) current density. [ABSTRACT FROM AUTHOR]

New attractive advances in electrode preparation for supercapacitor applications with rGO based composite materials are eye-catching attention of researchers. Cobalt oxide is considered as an effective electrode for full cell fabrication due to its high specific capacitance. Cost effective solvothermal method was used to prepare pristine Co 3 O 4 nanorods, NiCo 2 O 4 nanorods and NiCo 2 O 4 /rGO urchin like nanocilia structure composite materials. The complete electrochemical studies were used to check the obtained product electrochemical activity. The high specific capacitance values are obtained for NiCo 2 O 4 /rGO urchin like nanocilia composite electrode material which leads to design a full cell and make use as practical applications with illuminating red, green, blue LED source. The capacitive retention of 92.28% even after 5000 cycles achieved in GCD cyclic performance at a high current density implies its excellent stability. Image 1 [ABSTRACT FROM AUTHOR]

• Involvement of Ca in DyMnO 3 parent matrix results in increased specific capacitance. • Novel perovskite composites for usage in battery-type electrodes in supercapacitor applications. • Battery-type electrode performance of the composite made into a device showed capacity retention of 76% The Multifaceted properties of nanostructured rare earth perovskite manganite oxides have attracted much attention specifically for their applications in energy storage systems. In the present work, synthesis and physiochemical properties of calcium-substituted dysprosium perovskite manganite oxide nanocomposites and their potential applications as supercapacitors are examined. The perovskite structure and morphology of the designed nanocomposites are affirmed by the different analytical tools, including XRD, SEM, and TEM analysis. The structural analysis by XRD indicates the presence of DyMnO 3 perovskite phase with additional peaks of Dy 2 O 3 phase. The percentage of Dy 2 O 3 is gradually reduced with higher Ca substitution, from about 16% to 7%. The Halder-Wagner method indicates an increase of the microstrain and a decrease in crystallite size with the rise of Ca substitution. From Tauc's plot derived from DRS analysis, a slight increase in the band gap with the increase in Ca substitution is observed (2.55–2.62 eV). The surface elemental compositions and the valence states of individual elements analyzed using XPS analysis evidence the presence of Dy, Ca, Mn, and O. BET adsorption study indicates an increase in pore size, surface area, and pore volume with increasing Ca substitution concentration. When employed as a supercapacitor electrode material, Calcium-blend DyMnO 3 nanocompositeexhibits battery type behavior. This material shows a higher specific capacitance (capacity) of 531 Fg−1 (319.9 Cg−1) with comparatively low charge transfer resistance and better cyclic stability. We have assembled an asymmetric supercapacitor device using our prepared sample exhibiting energy density of 36.16 Wh/kg with better cyclic stability. This work provides new insights for designing future Dy 2 O 3 based supercapacitors. [ABSTRACT FROM AUTHOR]

• Cr 2 CT x MXene is synthesized via chemical etching using HF acid for 30 min. • The prolonged ultrasonication is used for preparing bifeo 3 /Cr 2 CT x MXene composite. • Electrochemical properties are evaluated towards HER and supercapacitor application. • BiFeO 3 /Cr 2 CT x MXene achieves η 10 of 128 mV and 53.3 mV dec−1 as the tafel slope. • Specific capacitance of 1678 f g −1 is achieved for bifeo 3 /Cr 2 CT x MXene electrode with long term stability. A multifunctional hierarchical Bismuth ferrite/chromium carbide (BiFeO 3 /Cr 2 CT x) MXene has been employed as both electrode material for supercapacitors as well as an electrocatalyst for electrocatalytic water splitting. Here, a facile method is suggested for synthesizing Cr 2 CT x MXene from the chromium aluminum carbide (Cr 2 AlC) MAX Phase. X-ray diffraction studies, Scanning electron microscopy, and high-resolution transmission electron microscopy indicate that the aluminum atomic layers are removed from Cr 2 AlC MAX structure. The electrochemical test reveals that the BiFeO 3 /Cr 2 CT x MXene composite, which is produced with less Al 2 O 3 , performs well in the hydrogen evolution reaction (HER) with a low overpotential of 128 mV in 1 M potassium hydroxide. 53.3 mV dec−1, and 0.16 Ω cm−2, respectively, are the values of the calculated Tafel slope and charge transfer resistance. In a dielectrode electrolysis system, BiFeO 3 /Cr 2 CT x MXene electrode needs only 1.81 V of cell potential to provide 10 mA cm−2 with long-term stability. The specific capacity of 671.2 C g −1 at a current density of 1 A g −1 is obtained for BiFeO 3 /Cr 2 CT x MXene electrode with 90% capacitance retention after 3000 cycles. The potential use of BiFeO 3 /Cr 2 CT x MXene towards HER and supercapacitor application is demonstrated by this study, which offers a gentle path for the fabrication of Cr 2 CT x MXene composites for energy storage and HER applications. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper reported the successful preparation and characterization of bio-activated carbon nanosheets (ACNSs) synthesized from tamarind (tamarind indicia) fruits shells (TFSs) by employing Chemical Vapor Deposition (CVD) tubular furnace. The preparation of pure ACNSs and also potassium hydroxide (KOH) activated carbon nanosheets (K-ACNSs) were made through a pyrolysis process with Argon (Ar) gas as an inert gas at 800 °C for 2h 30min, followed by further purifications of K-ACNSs. The scanning electron microscope (SEM) images of ACNSs and K-ACNSs explored with and without pores respectively. The SEM micrographs also explored 3D-porous microstructure sheets with thickness around 18–65 nm. Raman spectroscopy explored crystallinity, SP 2 order and graphitization at 1577–1589 cm−1. The major functional groups were also observed. The photoluminescence (PL) was analyzed for K-ACNSs materials and revealed carbon emission broad peak value at 521.3 nm. As prepared ACNSs and K-ACNSs active materials was applied for three-electrode materials of energy storage supercapacitor analysis of cyclic voltammeter for −0.4 – 0.15 V at scan rates of 10–100 mV/s. The electrochemical impedance spectroscopy (EIS) was performed with low Rct values of K-ACNSs as 0.65Ω when compared to pure ACNSs as 5.03Ω. Mainly, the galvanostatic charge-discharge test carried out in ACNSs and KCNSs materials was corresponded to 77 and 245.03 F/g respectively, with respect to 1 A/g current density. Finally, we promise that this reported novel tamarind bio-waste into conductive porous carbon nanosheets could develop future energy storage applications of biomass-derived carbons. • New technique to prepare 3D pores activated carbon nanosheets were demonstrated. • Carbonization/pyrolysis of tamarind shells in argon (Ar) leads graphitic carbon. • ACNSs specific capacitance observed was 77 F/g at 1A/g. • KCNSs specific capacitance observed was 245.07 F/g at 1A/g. [ABSTRACT FROM AUTHOR]

• Novel cost efficient and cleaner microwave synthesis of Fe 2 O 3 /MoS 2 /rGO is proposed. • Spherical Fe 2 O 3 nanoparticles are wrapped with the sheets of MoS 2 /rGO composite for better performance. • Fe 2 MG composite shows the improved supercapacitive behaviour with excellent cyclic stability. Cost-efficient microwave synthesisized α-Fe 2 O 3 /MoS 2 /rGO (Fe 2 MG) composite has been fabricated with promising energy storage characteristics. SEM and TEM analyses corroborate that the spherical α-Fe 2 O 3 nanoparticles are wrapped over MoS 2 and rGO sheets. The Fe 2 MG composite electrode exhibits high specific capacitance of 551 F.g−1 at 1 A.g−1 and improved cyclic stability with only 2.1% of capacitance loss after 2000 charge–discharge cycles at a high current density (30 mA.s−1). The Fe 2 MG composite is a suitable choice as an electrode material for supercapacitor and other electrochemical applications. [ABSTRACT FROM AUTHOR]

• Unique layered structural property enhanced electrochemical performance. • Increased specific capacitance of 1100 Fg−1 at 0.5 A/g at 0.5 V. • Better rate capability and stability achieved within studied range. • Product explored enhanced stability and retains 98.1% after 2000 cycles. Material storage property enrichment with good electrochemical performance is a foremost challenge. Cobalt hydroxide and reduced graphene oxide (rGO) composite synthesized via chemical precipitation method showed improved specific capacitance and cycle stability. The unique rGO layered structure in composite enhanced overall electrochemical performance. Raman spectra revealed disordered rGO structure and A 1g mode of Co(OH) 2 in composite. rGO/Co(OH) 2 electrode showed increased specific capacitance of 1100 Fg−1 at 0.5 Ag−1 with better rate capability and good stability (98.1%) after 2000 cycles. These results proved that rGO/Co(OH) 2 is a perfect electrode for electrochemical energy storage applications. [ABSTRACT FROM AUTHOR]

• Novel cost effective and greener microwave synthesis of Cu 2 O/MoS 2 /rGO is proposed. • Sheets of MoS 2 /rGO composite were wrapped over Cu 2 O nanoparticles for better performance. • Cu 2 MG exhibits enhanced supercapacitive behaviour with excellent cyclic stability. Novel Cu 2 O/MoS 2 /rGO nanostructure has been synthesized using simple and cost-effective microwave method. SEM and TEM observations confirm spherically-shaped Cu 2 O nanoparticles coated simultaneously with MoS 2 and rGO thin layers. The nanocomposite electrode exhibits high specific capacitance of 388F/g with excellent cyclic stability of 95.6% retained over 3000 charge–discharge cycles. The as-fabricated nanomaterial is a potential candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]