KOH Electrolyte Solution Research Articles

Sm0.5Sr0.5Co1-xNixO3-δ-A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions.

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air–metal batteries. ABO3-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm0.5Sr0.5Co1−xNixO3−δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm0.5Sr0.5Co0.8Ni0.2O3−δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec−1, and a current density of 6.01 mA cm−2 at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.

The Spin Modulation Stimulated Efficient Electrocatalytic Oxygen Evolution Reaction over LaCoO3 Perovskite.

Perovskite is a promising non-noble catalyst and has been widely investigated for the electrochemical oxygen evolution reaction (OER). However, there is still serious lack of valid approaches to further enhance their catalytic performance. Herein, we propose a spin state modulation strategy to improve the OER electrocatalytic activity of typical perovskite material of LaCoO3 . Specifically, the electronic configuration transition was realized by a simple high temperature thermal reduction process. M-H hysteresis loop results reveal that the reduction treatment can produce more unpaired electrons in 3d orbit by promoting the electron transitions of Co from low spin state to high spin state, and thus lead to the increase of the spin polarization. Electrochemical measurements show that the catalytic performance of LaCoO3 is strongly dependent on its electronic configuration. With the optimized reduction treatment, the overpotential for the OER process in 0.5 M KOH electrolyte solution at 10 mA cm-2 current density was 396 mV, significantly lower than that of the original state. Furthermore, it can mediate efficient OER with an overpotential of 383 mV under an external magnetic field, which is attributed to the appropriate electron filling. Our results show that electron spin state regulation is a new way to boost the OER electrocatalytic activity.

Highly selective porous separator with thin skin layer for alkaline water electrolysis

Advanced porous separators with thin selective skin layers to reduce the hydrogen permeation are developed for applications in alkaline water electrolysis. A thin skin layer based on crosslinked polyvinyl alcohol (cPVA) is fabricated on a porous substrate by a facile and scalable ultrasonic spray coating process. As the number of ultrasonic spraying cycles increases, the resulting separator demonstrates a decrease in the large-diameter pore fraction, an increase in the bubble-point pressure, and a reduction in the hydrogen permeability without a significant increase in the areal resistance. As a result, the optimized separator with a cPVA skin layer combines a low ionic resistance of 0.267 Ω cm2, a high bubble point pressure of 2.71 bar, and a low hydrogen permeability of 1.12 × 10−11 mol cm−2 s−1 bar−1. The electrolytic cell assembled with cPVAZ-30 achieves current densities of 861 mA cm−2 and 1890 mA cm−2 at 2.0 V and 2.6 V, respectively, in a 30 wt% KOH electrolyte solution at 80 °C.

NiCo2O4 nanostructures loaded onto pencil graphite rod: An advanced composite material for oxygen evolution reaction

Driving oxygen evolution reaction (OER) at extremely low overpotential and the blockage of oxygen gas inside the catalytic material leads to the deactivation of catalytic activity, therefore it is an essential step in electrochemical energy conversion systems, but still very challenging task. The clay minerals including bentonite and kaolinite are rich with plenty of active centers and favorable chemical composition for the catalysis applications but limited by the insulating properties, thus they cannot be used as an electrode material for the water splitting. The unique presence of clay minerals in the form of pencil graphite rod (PGR) and its attractive architecture enabled us to exploit advantageous features and use them as an in situ electrode for growth of metal oxide nanostructures for the electrolysis applications. The naturally inherent presence of SiO2 favors the catalytic properties and durability of the electrode whereas the MgO produces the abundant oxygen vacancies and Co3+ ions for OER process. Herein, we present a facile approach of using PGR as host substrate and co-catalyst for the loading of Co3O4, NiCo2O4 and NiO nanostructures and the modified electrode carried high porosity for easily bubbling of oxygen gas, plenty of intrinsic active centers coming from both clay minerals and metal oxides for excellent OER process. The fabricated electrode is physically well-characterized, and it has a natural ability to sustain a long term stability even at higher current densities and industrial electrolyzer conditions. The NiCo2O4/PGR, Co3O4/PGR, and NiO/PGR electrodes exhibit an overpotential of 234, 242 and 272 mV respectively at a current density of 100 mAcm−2 in 1.0 M KOH electrolytic solution. The presence of large number of oxygen vacancies through SiO2 and MgO, high Ni2+/Ni3+ and Co3+/Co2+ ratios, multi metal centers, large specific surface area, high pore volume, high electrochemical active surface area and fast charge transport within the NiCo2O4/PGR are the main reasons for its superfast OER kinetics. Thus, the proposed method of electrode design will pave a potential way for high performance electrochemical devices like metal air batteries, fuel cell and supercapacitors.

Structural and electrochemical performance of carbon coated molybdenum selenide nanocomposite for supercapacitor applications

Among the recent trends of supercapacitor electrode materials, transition metal dichalcogenides based composite materials have become popular due to their ability to have high electronic conductivity, variable oxidation states, large surface area, a porous structure. Herein we report, a composite material based on MoSe2 as electrode prepared using a standard single-step hydrothermal strategy. The structural and morphological study of the prepared material confirms the formation of the composite. The specific surface area has been estimated using BET technique and found to 522 m2g − 1 with average pore diameter as 4.6 nm. In all prepared composite electrodes, M@AC 1:5 electrode exhibits the highest specific capacity of 514 F g − 1 at a scan rate of 10 mV s − 1 for potential window 1 V in KOH electrolyte solution. The electrochemical impedance spectroscopy (EIS) study of the M@AC 1:5 electrode shows good agreement with cyclic voltammetry and galvanostatic charge-discharge storage mechanism. The aqueous symmetric cell fabricated of M@AC 1:5 with 6 M KOH electrolyte exhibits energy and power density 39.4 Wh kg−1 and 704.5 W kg−1 respectively. It shows long cycle stability with 90% capacitance retention and 100% coulombic efficiency even after 10,000 cycles. Further, the symmetric cell of M@AC 1:5 material was applied for lighting red LED, which illuminated for 22 min. The charging /discharging mechanism has been proposed based on finding of results through different characterizations. The asymmetric supercapacitor has also been designed using two different electrodes (first M@AC 1:5 and second synthetic MWCNT) and shows energy density of 14.9 Wh kg−1 and power density of 496 W kg−1 respectively. The capacitance retention is maintained up to 86.6% while coulombic efficiency recorded 100% for 10,000 cycles. Thus, obtained results highly encouraging and appropriate for the commercial applications.

Facile green synthesis of Molybdenum oxide nanoparticles using Centella Asiatica plant: Its photocatalytic and electrochemical lead sensor applications

The molybdenum oxide nanoparticles (MoO3 NPs) have been successfully synthesized via green combustion method using Centella asiatica plant powder. The powder x-ray diffraction (PXRD), Fourier transform infrared spectroscopic (FTIR), scanning electron microscopic (SEM) and diffuse reflectance spectroscopic (DRS) techniques were used to characterize the MoO3 nanoparticles. The PXRD patterns of the sample revealed pure hexagonal phase. The Scherrer's method was employed to find the crystallite size of the synthesized material and the result obtained was confirmed by the TEM analysis. The optical energy band gap value (Eg) of the sample was calculated using the Tauc relation, and it was found to be around 3.41 ​eV. The photocatalytic degradation of MoO3 NPs on Direct Green (DG) and Navy Blue (NB) dye was evaluated under UV light irradiation. The electrochemical study of prepared electrode with graphite powder in 0.1 ​M KOH electrolyte solution displayed superior redox potential output as intended by cyclic voltammetric and amperometric studies, where the material was employed for its sensing abilities such as a highly toxic metal like lead.

Preparation and capacitance performance of few-layer graphene

ABSTRACT The well-controlled graphene was prepared by pre-oxidisation, full-oxidisation and hydrothermal reduction of flake graphite. The graphene oxide (GO) reveals the overlapped few-layer structure and the reduced graphene oxide (RGO) shows well-dispersed few-layer structure. Raman spectra analysis indicates that the RGO shows higher B band/G band ratio value than GO, indicating well-restored SP2 carbon atom arrangement and crystal structure. Both fewer-layer GO and RGO were coated on nickel form for supercapacitor electrode application. The GO with sufficient hydroxyl, epoxy and carboxyl groups reveals low conductivity and low current response, which causes low specific capacitance of 0.36, 0.38 and 0.55 F g−1 at 0.5 A g−1 in Na2SO4, KOH and LiOH electrolyte solution, respectively. The RGO with high conductivity reveals the enhanced specific capacitance of 37.12, 51.80 and 61.31 F g−1 at 0.5 A g−1. The LiOH electrolyte with superior ionic diffusion coefficient leads to higher capacitance performance of fewer-layer GO and RGO than other electrolytes. The RGO shows much higher current response than GO at the same scan rate in cyclic voltammetry measurement, which is ascribed to its higher electroactivity. The similar capacitance enhancement of RGO was achieved through cyclic voltammetry-based capacitance and galvanostatic charge/discharge-based capacitance measurements. Accordingly, fewer-layer RGO reveals the superior electrochemical capacitance performance in LiOH electrolyte for the effective energy-storage application.

Double linker MOF-derived NiO and NiO/Ni supercapacitor electrodes for enhanced energy storage

Metal-organic frameworks (MOFs)-derived nanomaterials have emerged as novel electrodes for electrochemical energy storage application. Herein, MOF-derived NiO and NiO/Ni composite electrodes have been successfully synthesized by a unique double-linker MOF-strategy involving a series of calcination procedures (400 °C, 500 °C and 600 °C). The introduction of calcination temperature influenced both the textural and electrochemical properties of the MOF-derived NiO/Ni-400 and NiO/Ni-500 composite electrodes obtained at 400 °C and 500 °C respectively, as well as the NiO-600 electrode produced at 600 °C. With the combined benefits of improved uniform pore-size distribution and electrical conductivity, the composite electrodes delivered an enhanced supercapacitor performance with specific capacitances of 104.6 mAg−1 (NiO/Ni-400) and 37.4 mAg−1 (NiO/Ni-500) compared with 28.5 mAg−1 for the NiO-600 electrode at the same current density. Interestingly, NiO/Ni retained about 90% of its original capacitance after 1000 cycles when measured in 3 M KOH electrolyte solution. Furthermore, the electrochemical kinetic analysis used to probe the energy storage mechanism revealed pseudocapacitive behaviors at all tested scan rates; with NiO/Ni contributing 67% of the total capacitance at a scan rate of 5 mV/s which increased to 87% at 100 mV/s. The results obtained confirm that the approach described in this study is promising for the design of MOF-based electrodes for energy storage applications.

MXene-based O/Se-rich bimetallic nanocomposites for high performance solid-state symmetric supercapacitors

Herein, we developed a novel and high-performance supercapacitor material for by incorporating an electron-rich oxalate-modified cobalt and nickel selenide (CoNi(Ox)Se) on the surface of MXene. The formation of O/Se-loaded CoNi on the MX, affording enhanced electron transport between the electrodes. A high pseudocapacitive charge storage behavior of the CoNi(Ox)Se@MX composite is confirmed, exhibiting a specific capacitance of 1782 ​F ​g−1at 5 ​mV ​s−1in a KOH (1 ​M) electrolyte solution. This capacitance value is considerably higher than that of Co-based electrodes reported in the literature. Furthermore, electrochemical cyclic measurements indicated that material stability is retained after 1000 cycles at 5 ​A ​g −1. Notably, when set up as a solid symmetric capacitor, the synthesized electrodes exhibit a high energy density of 131.9 ​Wh kg−1at a power density of 7.2 ​kW ​kg−1, along with flexibility. The material possesses an excellent capacitance retention (95%) after 5000 cycles without loss of any metals/Se. The results indicate that the MX-based composite promoted rapid electrolyte diffusion, fast kinetics in terms of electron-transport, and high charge/discharge rates. Thus, CoNi(Ox)Se@MX structures may have the potential for the development of novel energy storage systems suitable for portable, miniaturized, and wearable power devices.

Investigations on electrochemical performances of Co(OH)2, Fe2O3 and Mn3O4 nanoparticles covered carbon micro spheres for supercapacitor application

The Co(OH)2, Fe2O3 and Mn3O4 nanomaterials layered over the surface of carbon spheres (CSs) were synthesized through the hydrothermal route. The prepared Fe, Mn oxide and Co hydroxide nanomaterials covered the surface of CSs were characterized for structural confirmation by X-ray diffraction analysis. Elemental vibrations are confirmed by Fourier transform infrared spectroscopic study. Shape and size of all metal oxides covered carbon spheres were observed by using scanning electron microscopy analysis and found to be spherical in shape. The electrochemical capacitive nature of the fabricated modified Co, Fe, Mn nanoparticles covered CSs working electrodes was examined by cyclic voltammetry and charge–discharge studies using 1 M KOH electrolyte solution. The comparison of electrochemical performances of prepared three metal oxides were done and it was found that Co(OH)2 layered carbon sphere exhibited higher specific capacitance value about 193.3 Fg−1 at a current density of 1 Ag−1.

Boosted electrocatalytic hydrogen production by methylene blue and urea and synergistic electrooxidation degradation

In this work, water electrolysis over α-MoO3 and h-MoO3 is investigated, and methylene blue (MB) and urea are added to further improve the electrocatalytic activity. α-MoO3 shows a higher activity than h-MoO3 for water electrolysis, which is mainly ascribed to Jahn–Teller effect of α-MoO3. When adding urea and MB, the anodic current density of α-MoO3 reach 310.98 and 403.72 mA/cm2 at 393 mV, which is 5.2 and 7.1 times higher than that (50.08 mA/cm2) in KOH electrolyte solution, respectively. It is proposed that the anodic oxidations of MB and urea are easier than water oxidation, thus increasing the anodic current greatly. Most importantly, the overpotential of hydrogen evolution reaction is also decreased obviously by MB and urea. At 40 mA/cm2, the cell voltages of urea/KOH (1.611 V) and MB/KOH (1.597 V) systems have decreased by 16.53% and 17.56%, compared with the KOH system (1.93 V), respectively. It is seen the system is energy-saving obviously. The innovative design can not only efficiently produce hydrogen but also can degrade environmental pollutants concurrently.

One-Dimensional Nise-Se Hollow Nanotubular Architecture As a Binder-Free Cathode with Enhanced Redox Reactions for High-Performance Hybrid Supercapacitors

Selenium enriched nickel selenide (NiSe-Se) nanotubes supported on highly conductive nickel foam (NiSe-Se@Ni foam) were synthesized using chemical bath deposition with the aid of lithium chloride as a shape directing agent. The uniformly grown NiSe-Se@Ni foam, with its large number of electroactive sites, facilitated rapid diffusion and charge transport. The NiSe-Se@Ni foam electrode, exhibited a superior specific capacitance value of 2447.46 F g-1 at a current density value of 1 A g-1 in a 1 M aqueous KOH electrolyte. Furthermore, a high-energy-density pouch-type hybrid supercapacitor (HSC) device was fabricated using the proposed NiSe-Se@Ni foam as the positive electrode, activated carbon on Ni foam as the negative electrode, and a filter paper separator soaked in a 1 M KOH electrolyte solution. The HSC delivered a specific capacitance of 84.10 F g-1 at a current density of 4 mA cm-2 with an energy density of 29.90 Wh kg-1 at a power density of 594.46 W kg-1 for an extended operating voltage window of 1.6 V. In addition, the HSC exhibited excellent cycling stability with a capacitance retention of 95.09% after 10,000 cycles, highlighting its excellent potential for use in the hands-on applications. The real-life practicality of the HSC was tested by using it to power a red light-emitting diode.

Excellent supercapacitive performance of graphene quantum dots derived from a bio-waste marigold flower (Tagetes erecta)

Marigold flower (MG; Tagetes erecta) derived Graphene quantum dots (GQDs) have been successfully reported for the fabrication of supercapacitor electrodes in charge storage devices. The GQDs have been synthesized through a hydrothermal route using biomass viz. Waste material (MG) without adding any hazardous chemicals. The successful formation of GQDs as elaborated has been confirmed by various analytical characterization techniques. The as-synthesized GQDs have been electrodeposited on the Ni foil (working electrode) with the help of PVDF (binder) and subsequently, cyclic voltammetry (CV) has been conducted to access specific capacitance, energy density, and other parameters. Moreover, the galvanometric charge/discharge (GCD) technique has been employed due to its accuracy and reliability. Maximum areal specific capacitance has been found as 1.6008 F/cm2 with the current density of 2.0 A/g even after loading a little amount of material on the electrode. The high magnitude of columbic efficiency (160.08), energy density (17.78 Wh/kg), and specific capacitance of 200 F/g at current density 2.0 A/g within a voltage range of −0.55 V to +0.25 V in 2 M KOH electrolyte solution indicate a good electrocapacitive performance of the as-synthesized material. Moreover, the as-synthesized GQDs have shown excellent capacitive retention after 1000th cycles which clearly embarks its sustainable electrocapacitive nature and henceforth offers outstanding potential for the applications in energy storage devices like supercapacitors.

A facile green synthesis of porous hexagonal cobalt pyrovanadate electrode for supercapacitors by deep eutectic solvent

Cobalt vanadate is a kind of promising electrode material for pseudo-supercapacitors because of their higher electrical conductivity, better electrochemical activity, and prominent specific capacitance than single metal oxides. In this paper, cobalt pyrovanadate (Co2V2O7) was primarily fabricated by a facile environment-friendly ionothermal method using a green deep eutectic solvent (DES) and followed the heat treatment in the air. The eutectic mixture discussed here was consisted of a hydrogen bond donor (urea) and acceptor (ChCl) in a 2:1 molar ratio. The as-prepared Co2V2O7 was porous hexagonal nanoplatelets, and its electrochemical performances were characterized by cycle voltammetry, galvanostatic charge/discharge and cycling stability tests in a three-electrode system with 2 M KOH electrolyte solution. The specific capacitance of the synthesized Co2V2O7 revealed 304 F g−1 at the current density of 1 A g−1. Surprisingly, it remained an excellent cycle performance with 103% in 100 charge/discharge cycles. Therefore, we have successfully presented a deep eutectic solvent derived routine to prepare porous hexagonal Co2V2O7 nanoplatelets electrode material.

Effect of Electrolyte Concentration on Electrochemical Performance of Bush Like α‐Fe2O3 Nanostructures

AbstractThe nano‐sized bush‐like α‐Fe2O3 particles were synthesized using sol‐gel auto combustion route. The structural characterization of obtained α‐Fe2O3 was performed by X‐ray diffraction (XRD) method to confirm its phase and crystallinity. The Scanning Electron Microscopy (SEM) confirmed the formation of bush‐like nanostructure which was further used for the electrochemical charge storage performance testing. The electrochemical performances of the synthesized electrode material were studied by using Cyclic Voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis in a three electrode configuration. The variation of specific capacitance values with the different molar concentration of electrolyte has been discussed. An enhancement in the specific capacitance has been observed up to 3 M KOH electrolyte solution. The maximum value of specific capacitance is 202.2 F g−1 which is obtained at a scan rate of 2 mV s−1 for 3 M aqueous KOH solution as electrolyte.

Silver Nanoparticles Embedded on Reduced Graphene Oxide@Copper Oxide Nanocomposite for High Performance Supercapacitor Applications.

In this work, silver (Ag) decorated reduced graphene oxide (rGO) coated with ultrafine CuO nanosheets (Ag-rGO@CuO) was prepared by the combination of a microwave-assisted hydrothermal route and a chemical methodology. The prepared Ag-rGO@CuO was characterized for its morphological features by field emission scanning electron microscopy and transmission electron microscopy while the structural characterization was performed by X-ray diffraction and Raman spectroscopy. Energy-dispersive X-ray analysis was undertaken to confirm the elemental composition. The electrochemical performance of prepared samples was studied by cyclic voltammetry and galvanostatic charge-discharge in a 2M KOH electrolyte solution. The CuO nanosheets provided excellent electrical conductivity and the rGO sheets provided a large surface area with good mesoporosity that increases electron and ion mobility during the redox process. Furthermore, the highly conductive Ag nanoparticles upon the rGO@CuO surface further enhanced electrochemical performance by providing extra channels for charge conduction. The ternary Ag-rGO@CuO nanocomposite shows a very high specific capacitance of 612.5 to 210 Fg−1 compared against rGO@CuO which has a specific capacitance of 375 to 87.5 Fg−1 and the CuO nanosheets with a specific capacitance of 113.75 to 87.5 Fg−1 at current densities 0.5 and 7 Ag−1, respectively.

Formation of hierarchical NiFe Prussian blue analogues/Prussian blue on nickel foam for superior water oxidation

A series of NiFe Prussian blue analogues (PBAs)/Prussian blue (PB) nanocubes (NizFe-PB-x-y) on nickel foam were synthesized using a one-pot redox reaction and deposition strategy. The growth and particle size of NizFe-PB-x-y can be adjusted by changing the ammonium persulfate concentration (x) and hydrothermal temperature (y). To explore the role of individual reactants, three other catalysts were synthesized by changing the reaction conditions, including sea urchin-like FeOOH, Fe4[Fe(CN)6]3 cube, and NiFe PBA/FeOOH grain. During the reaction, ammonium persulfate may acted as a promoter and oxidant, sodium citrate as a reducing agent and morphological regulator, potassium ferricyanide as a single iron source, and nickel foam as a nickel source and substrate. More importantly, compared with other catalysts, the electrochemically activated Ni0.59Fe-PB-3-110 catalyst manifests the most outstanding catalytic activity in 1.0 M KOH electrolyte solution, with current densities of 50 and 800 mA cm−2, requiring only 230 and 305 mV overpotential, respectively. It is anticipated that the novel strategy will not only contribute to the design and development of hierarchical three-dimensional PB or PBAs supported by conductive substrates, but also further promote their applications in the field of electrocatalysis and energy storage.

Synergistic approach of high-performance N-NiCo/PC environment benign electrode material for energy storage device

The development of sustainable electrochemical energy storage devices faces a great challenge in exploring highly efficient and low-cost electrode materials. Biomass waste-derived carbonaceous materials can be used as an alternative to expensive metals in supercapacitors. However, their application is limited by low performance. In this study, the combination use of persimmon waste-derived carbon and transition metal nitride demonstrated strong potential for supercapacitor application. Persimmon-based carbonaceous gel decorated with bimetallic nitride (N-NiCo/PC) was firstly synthesized through a green hydrothermal method. Electrochemical properties of N-NiCo/PC electrode in 6 M KOH electrolyte solution were evaluated using cyclic voltammetry (CV) and charge–discharge measurements. The N-NiCo/PC exhibited 320 F/g specific capacitance at 1 A/g current density and maintained 91.4% capacitance retention after 1500 cycles. Additionally, it exhibited a high energy density of 29.44 Wh/kg at 1000 W/kg power density and sustained 5.5 Wh/kg energy density even at a power density of 10,000 W/kg. Hence, the bimetallic nitride-based composite catalyst is a potentially suitable material for high-performance energy storage devices. In addition, this work demonstrated a promising pathway for transforming environmental waste into sustainable energy conversion materials.

Experimental and Computational Analysis of MnO2@V2C-MXene for Enhanced Energy Storage.

Herein, we studied the novel and emerging group of 2D materials namely MXene along with its nanocomposites. This work entails detailed experimental as well as computational study of the electrochemical behavior of vanadium carbide (V2CTx) MXene and MnO2-V2C nanocomposite with varying percentages of MnO2. A specific capacitance of 551.8 F/g was achieved for MnO2-V2C nanocomposite in 1 M KOH electrolyte solution, which is more than two times higher than the gravimetric capacitance of 196.5 F/g obtained for V2C. The cyclic stability achieved for the MnO2-V2C nanocomposite resulted in a retentivity of 96.5% until 5000 cycles. The c-lattice parameter achieved for MXene is 22.6 Å, which was 13.01 Å for MAX phase. The nanocomposite resulted in a c-lattice parameter of 27.2 Å, which showed that the spatial distance between the MXene layers was efficiently obtained. The method of wet etching was used for the preparation of pristine MXene and the liquid phase precipitation method was opted for the synthesis of the MnO2-V2C nanocomposite. Density functional theory calculation was exercised so as to complement the experimental results and to understand the microscopic details, such as structure stability and electronic structure. The current report presents a comprehensive experimental and computational study on 2D MXenes for future energy storage applications.

Microwave-assisted thin reduced graphene oxide-cobalt oxide nanoparticles as hybrids for electrode materials in supercapacitor

In recent times, microwave synthetic strategies have been considered as one of the facile methods for the development of efficient supercapacitor electrodes. Reduced graphene oxide containing cobalt oxide (rGO@Co3O4/CoO) hybrids were synthesized via single-step microwave irradiation in which the uniform Co3O4/CoO nanoparticles were attached in thin layers of rGO nanosheets. During short time of single-step microwave irradiation process, three kind of phenomena occurs as (i) reduction and exfoliation of graphite oxide into rGO nanosheets, (ii) decomposition of cobalt(II) acetate into Co3O4/CoO nanoparticles and (iii) rGO nanosheets covers the Co3O4/CoO nanoparticles. The BET surface area and pore diameter range of rGO@Co3O4/CoO hybrids were 133.2 m2g−1 and 5–45 nm, respectively, which shows the mesoporous structure formation of hybrids. Electrochemical evaluations of rGO@Co3O4/CoO hybrids as electrode materials for supercapacitor shows specific capacitance of 276.1 F g−1 (scan rate of 5 mV s−1) and long-term cycling stability as 82.37% capacitance retention after 10,000 cycles (scan rate of 60 mV s−1) in 0.1 M KOH electrolyte solution. The Co3O4/CoO nanoparticles with conducting scaffolds rGO structure will pave an encouraging alternative for electrode materials and suggesting good potential for supercapacitors applications.