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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]

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]

Hydrothermal method was adapted to synthesis NiCoO nanoparticles by varying nickel and cobalt precursor concentration as 1:1, 1:2, and 1:3 ratios. X-ray diffraction (XRD) results revealed the spinel NiCoO structure belongs to $${\rm{Fd}}\overline {\rm{3}} {\rm{m}}$$ space group system with face-centered cubic crystal structure. Raman characteristic peaks observed at 495 and 654 cm explored E and A modes of spinel NiCoO product. Photoluminescence (PL) results revealed the hole recombination of Ni/Co ions from 3d-E and 3d-T electronic state of spinel NiCoO material. The characteristic Fourier transform infrared spectroscopy (FTIR) metal-oxygen bands appeared at 658 and 558 cm revealed the spinel-type crystal structure. SEM image revealed the NiCoO spherical nanoparticles formation with an average particle size of around 500 nm. The cyclic voltammetry studies revealed the estimated average specific capacitance value of NC3 (NiCoO spherical nanoparticles) as 542 F g relatively higher than NC1 and NC2. The electro impendence spectroscopy results explored the small arc formation in high frequency range and very low charge transfer resistance ( R ), which resulted high conductive active materials. The estimated specific capacitance for NC3 exhibited superior galvanstatic charging and discharging (GCD) characteristics with high specific capacitance of 294 F g at high current density of 1 A g and revealed that the obtained electrode is suitable for supercapacitor applications. Graphical abstract: Hydrothermal synthesis using an excess of Co source leads to smaller and more uniform particle size. This particle size and the slightly larger crystallite size formed in the materials leads to the improved electrochemical performance of the particles. [ABSTRACT FROM AUTHOR]

MXenes are emerging as the next-generation materials for energy storage due to their substantial surface area, exceptional conductivity, and abundant surface-terminating groups. However, the tortuous path for ion transfer within the restacked layers significantly limits the electrochemical performance of multilayered MXenes. To overcome this, interlayer spacers have been introduced. These spacers help mitigate ion diffusion barriers and enhance the accessibility of active sites, thereby improving the overall efficiency and longevity of MXene-based supercapacitors and related devices. In this study, a rational material is designed by incorporating CoFe 2 O 4 and g-C 3 N 4 into the layers of MXene through ultrasonication for supercapacitor application. The physicochemical properties of the synthesized materials have been comprehensively characterized using diverse techniques, revealing that MXene/CoFe 2 O 4 /g-C 3 N 4 has successfully evolved into a multilayered structure possessing enhanced surface area, low restacking tendency, high pore diameter, and excellent pore volume. Leveraging these properties, it performs as a viable material for fabricating the working electrode with a specific capacitance (C sp) of 1506.2 F g−1 at a current density of 5 A g−1 in 3 M KOH. It shows good stability with 89 % capacitance retention over 7000 cycles. An asymmetric supercapacitor (ASC) constructed with MXene/CoFe 2 O 4 /g-C 3 N 4 as positive electrode and activated carbon as negative electrode exhibits an energy density of 79.8 Wh Kg−1 and power density of 1343.3 W Kg−1. Furthermore, it shows a capacitive retention of 91 % over 10,000 cycles. This MXene based composite, with excellent capacitance and outstanding stability, offers an appreciable performance in the field of sustainable energy storage. [Display omitted] • A promising electrocatalyst, MXene/CoFe 2 O 4 /g-C 3 N 4 is prepared by ultrasonication method. • It acts as a potential electrode material with specific capacitance of 1506.2 F g−1 at current density 5 A g−1. • Capacitive retention of 89 % up to 7000 cycles. • MXene/CoFe 2 O 4 /g-C 3 N 4 exhibits an energy density of 79.8 Wh Kg−1 and power density of 1343.3 W Kg−1. [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]

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]

• 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]

Bi 2 O 3 rods/RGO composite has been synthesized by a simple precipitation and calcination method. The crystallnity, structural, and morphological features were studied by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM) techniques. The supercapacitor behavior was studied using cyclic voltammetry, galvanostatic charge discharge and impedance analysis, respectively. The Bi 2 O 3 rods/RGO nanocomposite exhibits a maximum specific capacitance of 1041 F g −1 at a current density of 2 A g −1 . The photocatalytic activity of Bi 2 O 3 rods/RGO composite was evaluated by photocatalytic degradation of methylene blue (MB) dye under visible-light irradiation. The enhancement of photocatalytic properties of Bi 2 O 3 rods/RGO composite attributed to the synergistic effect between Bi 2 O 3 rods and graphene sheets which effectively prevents recombination of the photogenerated electron-hole pairs in Bi 2 O 3 rods. The present study provides a new approach in improving the performance of Bi 2 O 3 rods/RGO composite in energy and environmental applications. [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]

[Display omitted] • Novel CeO 2 /MoS 2 /rGO (CeMG) ternary composites using microwave method is proposed. • CeMG shows excellent specific capacitance of 635 F.g−1 as compared to CeO 2. • CeMG shows 88.9% capacitance retained after 10,000 cycles at 20 A.g−1. There is a huge requirement for renewable energy resources to avoid the usage of fossil fuel attracted the researchers to work on the energy storage devices, such as supercapacitors. Herein, the novel synthesis of CeO 2 @MoS 2 @rGO (CeMG) ternary composite by two step microwave synthetic route that will be employed as an outstanding electrode material for supercapacitor. In particular, the morphology studies confirm that the cerium oxide has spherical morphology with the controlled size in the range of 12–15 nm embedded with the layered sheets of MoS 2 and reduced graphene oxide. The CeMG composites exhibit excellent specific capacitance of 635 F g−1 which is achieved at the current density of 1 A g−1 compared to the pure CeO 2. In addition, prolonged cyclic stability with 88.9% capacitance is retained after 10,000 cycles of charging and discharging. [ABSTRACT FROM AUTHOR]

A simple and cost-efficient microwave route has been adopted to synthesize CuO/MoS 2 /rGO (CuMG) nanostructure as a potential electrode for supercapacitor. The morphological investigation indicates that the nanoflakes of bare CuO are decorated with the layered MoS 2 /rGO nanostructures. CuMG composite exhibits a higher specific capacitance of 1445 F g−1 @1 A g−1 compared to 535 F g−1 @1 A g−1 for CuO. This result demonstrates that the addition of MoS 2 /rGO to CuO initiates the rapid migration of electrolyte ions. Moreover, this interesting nanocomposite possesses good cyclic stability; i.e. only 9.1% loss after 3000 charge-discharge cycles at the high-applied current of 30 A g−1. The excellent electrochemical properties of CuMG extend its usage as high performance electrode materials in next-generation energy storage applications. • Cost-effective synthesis of novel CuO/MoS 2 /rGO ternary composites using microwave method is proposed. • CuMG composite as an electrode material exhibits excellent specific capacitance of 1445 F g−1 as compared than that of CuO. • CuMG shows a good cyclic stability with only 9.1% loss even after 3000 charge-discharge cycles at 30 A g−1. [ABSTRACT FROM AUTHOR]

An electrochemically active composite material consisting of zinc vanadate (Zn 3 V 2 O 8) and nitrogen doped multi wall carbon nanotubes (N-MWNCT) was prepared using simple hydrothermal procedure. This attractive composite material was exploited as an electrode for the supercapacitor application. The multiple oxidation states of vanadium and stable zinc rendered wide range of redox reaction with MWCNT which was explored with K 2 SO 4 neutral electrolyte. The electron microscopic analysis along with XRD and XPS confirmed the formation of ternary composite. The unique combination of Zn 3 V 2 O 8 and N-MWNCT showed a specific capacitance of 403 F g−1 with better stability of 79% for 5000 cycles. The presence of N-MWCNT enhanced the performance of the ZVC composite by providing structural support which significantly reduced the charge transfer resistance R ct (1.3 Ω) and series resistance R s (1.8 Ω) by providing synergetic effects. The results have demonstrated the potential scope of ZVC for the energy storage device. Unlabelled Image • Electrochemically active composite of zinc vanadate (Zn3V2O8) and (N-MWNCT) was prepared using hydrothermal procedure. • Electron microscopic analysis along with XRD and XPS confirmed the formation of ternary composite. • The unique combination of Zn3V2O8@MWNCT (ZVC) recorded a specific capacitance of 403 F g-1 which is 89% higher than bare Zn3V2O8. • Considerable reduction in charge transfer resistance Rct (1.3) and series resistance Rs (1.8) for ZVC composites. • ZVC based asymmetric supercapacitor demonstrated better cyclic stability of 81% for 5000 cycles. [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]