Development of active materials capable of delivering high specific capacitance is one of the present challenges in supercapacitor applications. Herein, we report a facile and green solvothermal ...approach to synthesize graphene supported tungsten oxide (WO3) nanowires as an active electrode material. As an active electrode material, the graphene–WO3 nanowire nanocomposite with an optimized weight ratio has shown excellent electrochemical performance with a specific capacitance of 465 F g–1 at 1 A g–1 and a good cycling stability of 97.7% specific capacitance retention after 2000 cycles in 0.1 M H2SO4 electrolyte. Furthermore, a solid-state asymmetric supercapacitor (ASC) was fabricated by pairing a graphene–WO3 nanowire nanocomposite as a negative electrode and activated carbon as a positive electrode. The device has delivered an energy density of 26.7 W h kg–1 at 6 kW kg–1 power density, and it could retain 25 W h kg–1 at 6 kW kg–1 power density after 4000 cycles. The high energy density and excellent capacity retention obtained using a graphene–WO3 nanowire nanocomposite demonstrate that it could be a promising material for the practical application in energy storage devices.
Enhancing the performance and stability of the low-cost materials for electrochemical energy storage device is an important aspect. Herein, we report microwave-assisted solvothermal synthesis of ...three-dimensional (3D) spherical CuO structures composed of either one-dimensional (rod-like) or two-dimensional (2D) flake-like building blocks by varying the reaction medium, i.e., water and ethylene glycol (EG). A higher EG in the reaction medium facilitates formation of the flake-like structures. A specific surface area of 168.47 m2 g–1 is achieved with the 3D flower-like CuO, synthesized using copper acetate precursor in 1:3 water/EG solvent ratio. The same sample delivers a specific capacitance of 612 F g–1 at an applied current density of 1 A g–1 and shows high stability with capacity retention of 98% after 4000 galvanostatic charge–discharge cycles. The high specific capacitance of flower-shaped CuO architecture is attributed to large surface area and availability of sufficient pores for ions diffusion. Furthermore, two-electrode asymmetric supercapacitor device is fabricated using the 3D flower-shaped CuO as positive electrode and activated carbon as negative electrode, which shows an energy density of 27.27 Wh kg–1 at a power density of 800 W kg–1. This underlines the potential of inexpensive CuO architecture as an active material for energy storage devices.
•Bi2Se3−MnO2 nanotube composite synthesized by redox mediated methodology.•Evolution of intercalation pseudocapacitance in nanotube composite.•Synergistic combination of intercalation and redox ...pseudocapacitance.•Integrated high energy and high power density performance.
Layered materials exhibit exclusive electrochemical properties centered on interlayer spaces. However, slow kinetics and poor cycling stability restrict overall performance. A possible solution to deliver high energy storage is by interfacial modification of layered materials, which can structurally allow the occurrence of intercalation pseudocapacitance at redox-capacitance timescale. In this work, MnO2 has been intercalated in-situ in layered Bi2Se3 for the first time to give Bi2Se3−MnO2 nanotube composite. Structural and morphological characterizations have been conducted elaborately by several experimental and theoretical studies. Electrokinetic measurements reveal a dominant capacitive mechanism of 69% at 60 mV s − 1. Ex-situ XRD analysis after electrochemical charge-discharge cycles show reversible shifts in c-axis containing Bi2Se3 (015) plane, which confirms intercalation pseudocapacitance. The nanocomposite demonstrates high specific capacitance (438 F g − 1 at 1 A g − 1 in a three-electrode system) in a wide potential window of 2 V. Moreover, a symmetric two-electrode system for Bi2Se3−MnO2 exhibits a high energy density of 62 Wh kg−1 and a power density of 2.7 kW kg−1 at 1 A g − 1 and 10 A g − 1, respectively, along with capacitance retention of 86% after 2000 cycles. The study gives promising direction to design integrated high energy and power density intercalation pseudocapacitive materials.
Intercalation pseudocapacitance in Bi2Se3−MnO2 nanotube composite for high electrochemical energy storage Display omitted
An efficient, cost-effective, and earth-abundant catalyst that could drive the production of hydrogen from water without or with little external energy is the ultimate goal toward hydrogen economy. ...Herein, nanoplates of tungsten oxide and its hydrates (WO3·H2O) as promising electrocatalysts for the hydrogen evolution reaction (HER) are reported. The square-shaped and stacked WO3·H2O nanoplates are synthesized at room temperature under air in ethanol only, making it as a promising green synthesis strategy. The repeated electrochemical cyclic voltammetry cycles modified the surface of WO3·H2O nanoplates to WO3 as confirmed by X-ray photoelectron and Auger spectroscopy, which leads to an improved HER activity. Hydrogen evolution is further achieved from distilled water (pH 5.67) producing 1 mA cm–2 at an overpotential of 15 mV versus the reversible hydrogen electrode. Moreover, WO3·H2O and WO3 nanoplates demonstrate excellent durability in acidic and neutral media, which is highly desirable for practical application. Improved hydrogen evolution by WO3(200) when compared to that by Pt(111) is further substantiated by the density functional theory calculations.
Recently, Perovskite oxides have become the primal components for the establishment of electrochemical conversion device like Proton conducting Ceramic Fuel Cells (PCFC). Owing to the excellent ...chemical stability and rapid proton diffusion, barium zirconate (BaZrO3) is acknowledged as the emerging PCFC electrolyte material. Nanoionics envisions the distinct features, behaviour, and efficiency of the material and endorses its chemical reactivity and electrical property against harsh environment with enlarged surface area and quantum effect. To enhance the material property, barium zirconate (BaZrO3) has been prepared by different novel synthesis techniques altering the synthesis parameters and conditions. Dopant incorporation into pristine BaZrO3 accelerate the mobility of protons and increases the proton conductivity at reduced temperature (600–700 °C). This featured article demonstrates the elemental properties, synthesis methods and the role of trivalent dopant impurities which helps to expand the scope of PCFC application with optimized output performance.
Transition metal chalcogenides have been widely studied as a promising electrocatalyst for the hydrogen evolution reaction (HER) in acidic conditions. Among various transition metal chalcogenides, ...tungsten disulfide (WS2) is a distinguishable candidate due to abundant active sites and good electrical properties. Herein, we report a facile and selective synthetic method to synthesize WS2 with an intriguing two-dimensional nanostructure by using cysteine (C3H7NO2S) as a chemical agent. In addition, nitrogen can be incorporated during chemical synthesis from cysteine, which may be helpful for enhancing the HER. The electrocatalytic activity of N-doped WS2 exhibits a promising HER in acidic conditions, which are not only higher than W18O49 nanowires and hex-WO3 nanowires, but also comparable to the benchmark Pt/C. Moreover, excellent electrocatalytic stability is also demonstrated for acidic HER during long-term tests, thus highlighting its potential use of practical applications as an electrolyzer.
Exploring semiconductor materials with superior photocatalytic activity is desirable to mitigate the crisis associated with rapid depletion of fossil fuels and environmental pollutions. Herein we ...report the synthesis of orthorhombic stacked WO3·H2O square nanoplates by mixing WCl6 (0.025 M) in ethanol at room temperature via a precipitation method. On the other hand, hierarchical urchin-like W18O49 nanostructures composed of nanowires were synthesized from the preceding solution within 10 min through a microwave-assisted route. The morphology evolution from nanoplates to nanowires proceeds through a dissolution and recrystallization mechanism, as demonstrated in detail by varying the reaction duration and temperature. The as-synthesized WO3·H2O nanoplates and W18O49 nanowires were employed for the photocatalytic degradation of rhodamine B and photoelectrocatalytic hydrogen generation through water splitting in a neutral medium. Furthermore, the as-synthesized W18O49 nanostructures are employed as electrocatalysts for hydrogen evolution reaction in both acidic and neutral electrolytes. The enhanced electrocatalytic and photocatalytic activity of W18O49 nanostructures are attributed to their larger surface area, oxygen vacancies, and faster charge transport properties. This work demonstrates a greener and simpler way to synthesize a promising defect-rich material (W18O49) in a short duration and its potential in electrocatalytic and photoelectrocatalytic hydrogen generation, and for degradation of pollutant.
Porous carbon nanosheets are synthesized from chemical activation of turmeric leaves and tested as electro-active material for high-performance supercapacitor application.
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•A 2D ...nanosheet porous carbon is obtained from turmeric leaves via a simple chemical activation process.•N and O-containing functional groups are present in situ in the partially graphitized carbon.•A hierarchical nanostructure with high specific surface area and pore volume is achieved.•A fabricated symmetric supercapacitor device delivered high energy-power density performance.
It is a formidable challenge to develop efficient and low-cost nanostructured carbonaceous materials for electrochemical energy storage application. Herein, a hierarchical porous carbon nanosheet is successfully synthesized in a facile manner from turmeric leaves by a two-step chemical activation strategy using KOH activator. The biomass-derived interconnected two-dimensional (2D) carbon framework prepared at 900 °C presents high self-doped N (11.42 at%) and O contents (7.77 at%) together with specific surface area and pore volume of 541 m2/g and 0.47 cm3 g−1, respectively. Consequently, the resultant electroactive functional material shows a specific capacitance of 389 and 310 F/g at a current density of 1 A/g in acidic and neutral electrolytes, respectively. Additionally, an assembled symmetric supercapacitor device in Na2SO4 electrolyte delivers good capacitance retention of 90 % after 5000 consecutive charge–discharge cycles along with high specific energy (39.44 Wh kg−1at specific power of 0.49 kW kg−1). This work provides a cost-effective, eco-friendly and sustainable outlook to prepare high-valued porous carbons from reliable biomass sources for high-performance supercapacitor application.
In this work, a wet-chemical followed by thermal annealing strategy is employed to prepare Ni0.5Cu0.5Co2O4 without using any template. The material with flower-like architecture is composed of ...several nanorods that exhibit good textural properties (surface area: 120 m2/g, pore volume: 0.35 cc/g) and exposed facets and thus offers numerous electroactive sites for ion diffusion at the vicinity of electrode–electrolyte. The fabricated electrode with Ni0.5Cu0.5Co2O4 exhibits a higher specific capacitance of 367.4 F/g compared to fabricated electrodes using NiCo2O4 (280.3 F/g) and CuCo2O4(133.5 F/g) at the current density of 1 A/g. The material also exhibits high electronic conductivity (low R ct) and impressive cycling stability (89% retention after 5000th cycle). The combination of the synergistic effect of the variable oxidation state of three metal ions, large electroactive surface area, and fast ion diffusion through the porous structure are responsible for this high performance supercapacitive property of the ternary metal oxide. An assembly of four equivalent asymmetric supercapacitors (fabricated using activated carbon as cathode and Ni0.5Cu0.5Co2O4 as anode) connected in series is demonstrated for powering LEDs. The fabricated device has been shown to achieve 53.08 W h kg–1 energy density at the power density of 700.3 W kg–1 and withholding the columbic efficiency of 99.6% after a 5000 cyclic runs at 5 A/g applied current density. Moreover, the output efficiency of the device is better or comparable to most of the Ni- and Co-based asymmetric devices reported earlier.
Over the past decades, tremendous effort has been made to enhance the water‐splitting via fabricating eco‐friendly electrocatalyst with increased conductivity, and large number of accessible active ...sites in lab scale. However, the development of earth abundant efficient electrocatalyst with superior activity for ‐seawater‐splitting remains a great challenge for the researchers. In this regard, self‐supported catalysts are found to be the most promising candidates, they have the features of increased loading, superior adhesion, rapid mass and charge transfer, and easy wettability for large scale hydrogen production via electrochemical seawater splitting. This review investigates different fabrication processes for the self‐supported catalyst, emphasizing their distinct characteristics that contribute to improved activity. Furthermore, we provided a detailed elucidation of the procedure and characteristics of seawater splitting, emphasizing the most recent progress in the creation of self‐supportive catalyst for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and bifunctional activity. We have also examined the current barriers and potential prospects for advancing the utilization of self‐supported catalysts in the process of seawater splitting.
Self‐supported catalysts are the best candidates for large‐scale hydrogen production through electrochemical seawater splitting because to their increased loading, adhesion, mass and charge transfer, and wettability. The present review investigates the methodologies for producing self‐supported catalysts and explores their distinctive characteristics that enhance catalytic activity along with the upcoming challenges in self‐supported catalyst for seawater splitting.
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