Na2SO4 Electrolyte Solution Research Articles

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.

Preparation of Ta2O5 nanoparticles by using cathode glow discharge electrolysis

Tantalum pentoxide nanoparticles (Ta2O5 NPs) were fabricated by cathode glow discharge electrolysis (CGDE) generated between a needle-like platinum wire cathode and a tantalum foil anode in 6 g L−1 Na2SO4 electrolyte solution containing 5 ml hydrofluoric acid (HF) and 0.075 g cetyltrimethyl ammonium bromide (CTAB). The chemical structure, composition and morphology of the obtained powder were analyzed by using XRD, FT-IR, SEM/EDS, XPS and UV–vis DRS. The results found that Ta2O5 NPs with orthorhombic structure and wide band gap (3.6 eV) are successfully fabricated at 500 V discharge voltage in about 3 h. CTAB as a stabilizing agent can reduce the agglomeration due to forming CTA+ and attaching the surface of the synthetic products. A possible preparation mechanism of Ta2O5 NPs is proposed. Firstly, the tantalum foil anode is oxidized to form a compact Ta2O5 layer. Then, Ta2O5 surface is etched to form soluble [TaF7]2− complexes in the presence of HF. After that, soluble [TaF7]2− complexes can react with H2O to form Ta(OH)5. Finally, Ta(OH)5 is further converted to Ta2O5 from plasma-liquid interface into solution.

Selectivity adsorption of sulfate by amino-modified activated carbon during capacitive deionization

ABSTRACT Capacitive deionization (CDI) is an environmentally friendly desalination technique with low energy consumption. However, unmodified carbon electrode materials have poor sulfate selectivity and adsorption capacity. In this work, to improve sulfate selectivity, we prepared activated carbon materials loaded with different amino contents by grafting amino groups via acid treatment for different times. In the competitive ion adsorption experiments, the sulfate selectivity of AC was only 0.64 and the amino-modified AC increased by 1.98-2.52 times due to the formation of stronger hydrogen bonds between the amino group and sulfate. AC-NH2-4 had the best selectivity and the sulfate selective coefficient was 2.25. The desorption of sulfate was 92.46% within one hour. In addition, the surface of the amino-modified activated carbon showed significantly improved electrochemical properties and better capacitance. The specific capacitance of amino-modified AC in different electrolyte solutions was consistent with the competitive adsorption results. The specific capacitance of amino-modified AC in Na2SO4 electrolyte solution was the highest. The modified electrode material also had the advantages of a higher adsorption capacity and excellent regeneration performance after continuous electric adsorption–desorption cycles. Therefore, it may have development potential to selectively adsorb sulfate in practical applications.

Influence of supporting electrolyte on electrochemical formation of copper nanoparticles and their electrocatalytic properties

Comparative analysis of copper nanoparticles (CuNPs) obtained by electrodeposition on highly oriented pyrolytic graphite (HOPG) substrates from different supporting electrolytes containing sulphate anions, was performed. Voltammetric results indicated that Cu electrodeposition follows a diffusion-controlled nucleation and crystal growth model for three solutions studied (Na2SO4, H2SO4 and Na2SO4+H2SO4). Na2SO4 solution was found to be most effective because the copper reduction occurs at most positive potential value, reaching the highest current density. Analysis of potentiostatic current transients revealed that the process can be described predominantly by a model involving 3D-progressive nucleation mechanism, which was corroborated by scanning electron microscopy (SEM) analysis. SEM images showed high density of hemispherical shaped Cu particles of different sizes (mostly between 80-150 nm), randomly distributed on the HOPG surface for Na2SO4 electrolyte solution. In the presence of H2SO4, the size dispersion decreased, resulting in particles with greater diameters (up to 339 nm). The use of electrolyte solution with Na2SO4+H2SO4 revealed lower particle density with a considerable crystal size dispersion, where very small crystallites are prevailing. Cyclic voltammetry was used to evaluate qualitatively the catalytic activity of CuNPs deposited from three electrolyte solutions towards the nitrate reduction reaction. An enhanced catalytic effect was obtained when copper particles were prepared from either Na2SO4 or H2SO4 supporting electrolytes.

Silicon nanowire-hydrogenated TiO2 core-shell arrays for stable electrochemical micro-capacitors

In this paper, we fabricated silicon nanowire-TiO2 core-shell arrays in a two-step process. First, silicon nanowire arrays (SiNW) were prepared in HF/AgNO3 aqueous solution using metal-assisted chemical etching of bulk silicon. Then, atomic layer deposition (ALD) technique was applied to coat a 20 nm thin shell TiO2 film. The TiO2/SiNW substrates were afterward annealed at 400°C in hydrogen atmosphere for 4 h and tested as electrode materials for electrochemical micro-capacitors. The electrochemical features of the constructed H−TiO2/SiNW electrode were assessed in an aqueous 1 M Na2SO4 electrolyte solution and revealed that the specific capacitance increased six times compared to non-annealed TiO2/SiNW and 20-fold compared to a reference SiNW electrode under the same operating conditions. Importantly, H−TiO2/SiNW also displayed a high stability over 30,000 cycles at 0.1 mA cm−2 with an overall decrease of 19% of the initial capacitance. The hydrogen treatment increased the density of hydroxyl group and enhanced the carrier density on TiO2 surface improving the capacitive properties of H−TiO2/SiNW.

Gradient oxygen vacancies in BiVO4 olive-seeds nanostructure for electrochemical supercapacitor applications

In recent years, humans' increasing necessity and consumption of energy and the lack of energy-related issues have drawn considerable attention due to high power density, cyclic performance, and highly safe. Herein, we have designed and reported new Olive-Bismuth vanadate (O-BV) electrodes serving as excellent electrochemical materials for supercapacitors prepared by a simple solvothermal method. The supercapacitive features were examined by cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. The cyclic voltammetric analyses were performed using three different electrolytes, including aqueous Na2SO4, KOH, and NaOH electrolyte solution in 1 M concentration. The as-prepared O-BV electrode exhibits a significant specific capacitance of 977 Fg-1 at a scan of 5 m V−1 in 1 M NaOH electrolyte solution. Furthermore, the Olive-Bismuth vanadate electrode was achieved outstanding performance of cyclic stability after 2000 cycles and retained 86% of its initial capacitance. The excellent specific capacitance and superior cyclic stability highlight the potential of the Olive-Bismuth vanadate material as an active electrode for high-performance supercapacitors.

Physicochemical properties of surface modified ZnFe2O4 nanocomposite incorporated with bio‐templated kapok fiber for photoelectrochemical application

Surface‐modified zinc ferrite nanocomposites were successfully prepared thru ultrasonic impregnation technique by taking kapok fiber as a bio‐template. This work demonstrates a fast preparation method to produce the bio‐templated ZnFe2O4 composite photocatalyst. The templating method for photocatalyst is favorable due to the benefit of a large surface area for solar harvesting activities in the photoelectrochemical (PEC) system. Comprehensive physicochemical analyses have successfully determined the unique properties of the prepared catalysts. The pure mimetic fibrous catalysts were successfully fabricated as photoelectrodes on the fluorine tin oxide substrate using electrophoretic deposition technique for PEC measurement. The ranging ratio of precursors used to prepare bio‐templated zinc ferrite catalysts shows an effect on their surface structure then influences the photocurrent density performance of PEC analysis. The ZF1 photoanode at 1:1 Zn/Fe ratio has generated the highest photocurrent density of 58 μA cm−2 at 0.7 V vs. Ag/AgCl compare to other samples in 0.5 M Na2SO4 electrolyte solution under 100 mW cm−2 light irradiation. The high photocurrent density was attributed to the enhancement in light‐harvesting properties, fine surface structure, and high charge transfer properties that correlate with the composite ratio's alteration. The bio‐templated zinc ferrite photocatalysts are a promising photoanode in PEC activities.

Preparation of polyaniline nanorods/manganese dioxide nanoflowers core/shell nanostructure and investigation of electrochemical performances

A hierarchical polyaniline nanorod/manganese dioxide nanoflower (PANI/MnO2) core/shell nanostructure was successfully constructed through in situ polymerization, in which PANI nanorods work as the core and K-birnessite-type MnO2 act as the shell. The core/shell nanostructure effectively increases active surface areas and obviously decreases the ion transmission distance, which is conducive to the efficient contact and transfer of ions. The morphology, the chemical structure, and the crystal phase of PANI/MnO2 were measured by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Moreover, its supercapacitor behaviors were analyzed by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests, showing that this nanostructure exhibits better electrochemical activity and higher capacitance performance than pure PANI nanorods and pure MnO2. In 1.0 M Na2SO4 electrolyte solution, the specific capacitance of PANI/MnO2 is 215 F g−1 at 0.30 A g−1.

An investigation of the microstructural effects on the mechanical and electrochemical properties of a friction stir processed equiatomic CrMnFeCoNi high entropy alloy

The electrochemical properties of a friction stir processed (FSPed) equiatomic CrMnFeCoNi high-entropy alloy (HEA) was investigated in an aerated 0.5 M Na2SO4 electrolyte solution at room temperature. The microstructural analysis reveals a highly refined stir zone (SZ) with an average grain size that decreases from the top region of the SZ to the bottom region of the SZ (also known as shear-processed zone; SPZ). However, the region below the SPZ, (i.e. below the plunge depth) experienced an increase in average grain size and dislocation densities compared to the other regions. There is no secondary phase observed in the FSPed region, however, the microstructural evolution in the FSPed region affects the electrochemical behavior of the HEA. Cr2O3 passive layer was observed to form on the FSPed HEA, leading to excellent corrosion properties from the polarization corrosion tests. Grain refinement in the SZ enhances the rapid formation of the passive layer, thus, leading to better corrosion properties in the front surface of the FSPed HEA. The localized corrosion behavior of the FSPed HEA was predicted to be caused by the micro-galvanic nature of the HEA, which leads to an increase in polarization at the anodic sites (pits). A numerical model was established using the corrosion parameters from the experiment to simulate the localized corrosion behavior on the surface of the FSPed HEA in a neutral environment. The predicted initial pitting potential and corresponding current density agree well with the experimental results. The model is also capable of tracking the dissolution of the pits over longer periods.

High performance solid state symmetric supercapacitor based on reindeer moss-like structured Al(OH)3/MnO2/FeOOH composite electrode for energy storage applications

Developing an efficient, clean, sustainable, and reliable energy storage system is still a key challenge to resolve the growing demands of energy consumption. In this regard, supercapacitor becomes one of the foremost promising and emerging types of energy storage systems comprising properties of traditional batteries and conventional capacitors. Herein, a binder-free composite electrode of Al(OH)3/MnO2/FeOOH (AMFO) has been synthesized on stainless steel substrate via a facile, eco-friendly, and cost-effective Layer by Layer method at room temperature. The high resolution scaning electron microscopy reveals the mesoporous reindeer moss-like morphology of the synthesized electrode. The supercapacitive behaviour of the synthesized electrode has been explored in 1 M Na2SO4 electrolyte solution by using electrochemical measurement. The highest specific capacity of 2557 C g−1 has been obtained at a scan rate of 5 mV s−1 having wide potential range (−1.10 to 1.05 V). Further, a symmetric prototype supercapacitive device has been fabricated by coupling the AMFO electrodes. The high specific capacitance of 511 F g−1 has been obtained with ultra-high energy and power densities of ∼443 Wh kg−1 and ∼13 kW kg−1, respectively. These results indicate that this electrode has potential practical applications as a power backup, portable electronic device, and energy storage system.

The Role of PEG 6000 and PVP as Stabilizing and Surfactant Agents in the Photoelectrochemical Properties of BiVO4 Monoclinic Structure

Nanocrystalline BiVO4 on monoclinic phase was obtained by a modified-solution combustion synthesis (SCS) using poly(ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP) as stabilizing and surfactant agents, respectively. An active photoanode was built using a simple procedure by dip-coating deposition process on fluorine-doped tin dioxide (FTO). The structure, morphology and optical properties of FTO/BiVO4 photoanode were evaluated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and diffuse reflectance UV-Vis spectroscopy. The photoelectrochemical performance measurements were carried out by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) under InGaN blue light emitting diode (LED) illumination condition (about 450 nm). In Na2SO4 electrolyte solution, the electrode has presented better photoelectroactivity than in NaNO3 solution, as evidenced by photoelectrochemical parameters such as: the highest photocurrent density (js) value, cathodic shifts of the onset potential (OP) and lower charge-transfer resistence (Rct). In the methyl orange (MO) degradation reaction the FTO/BiVO4 electrode has presented high photoelectroactivity, where the estimated kinetic constant rate (kobs) is 4.74 × 10−3 and 7.54 × 10−3 min−1 in NaNO3 and Na2SO4 solutions, respectively. This remarkable performance of the as-prepared electrode is due to the morphological BiVO4 structure,with elongated-shape nano-sized domain particles, besides the considerable porosity and roughness levels on electrode surface.

Discoloration of azo dye Brown HT using different advanced oxidation processes

In this study, known combinations of Advanced Oxidation Processes (AOPs, namely Electro-Fenton (EF), Photo-Electro-Fenton (PEF), Electro-Oxidation (EO), and EO/Ozone (O3) were compared for the discoloration of tannery industry azo dye Brown HT (BHT). The different AOPs were tested in a 0.160 L batch electrochemical stirred thank reactor using Boron Doped Diamond (BDD) electrodes. The influence of parameters such as the current density (j) and the initial BHT concentration were to exanimated on the efficiency of all the tested processes. The oxidation tendency of EF, and PEF were compared with those of EO and O3, based on their efficiency for BHT discoloration, which resulted as PEF > EF > EO > O3. The AOPs showing the best oxidation performance was PEF which, using Na2SO4 (0.05 M) electrolyte solution and Fe2+ (0.5 mM), pH 3.0, j = 71 mA cm−2, and 500 rpm process, achieved 100% discoloration and 80% chemical oxygen demand (COD) abatement after 60 min of treatment for two initial BHT concentrations (50 and 80 mg L−1). The process accounted for a current efficiency of 30% and energy consumption 2.25 kWh (g COD)−1 through the discoloration test. The azo dye gradually degraded, yielding non-toxic oxalic, oxamic, and glyoxylic acid, whose Fe(III) complexes were quickly photolyzed.

Fabrication of WO3/RGO/Ni:FeOOH heterostructure for synergistically enhancing photoelectrochemical water oxidation

The instability and low activity of WO3 is the hot-topic for photoelectrochemical (PEC) water splitting, which is decreased by a sluggish interfacial kinetics and incomplete water oxidation. Aiming at such issues, we designed a ternary WO3/RGO/Ni:FeOOH photoanode, which exhibits 2.05 times larger photocurrent (1.32 mA cm−2) than the WO3 NFs in 0.5 M Na2SO4 electrolyte solution, accompanied with 83 mV cathodic shift of onset potential. These results demonstrates PEC response can occurs only in Ni:FeOOH but not FeOOH. Therefore, Ni:FeOOH acting as bi-functional modifier, can not only increase light absorption but also promote charge transfer process by forming p-n heterojunction with the WO3 NFs. Besides, RGO forming a continuously conducting network can further improve charge separation process. Owing to their synergistic effects, the Faradaic efficiency and stability are both improved compared to its counterparts and the bare WO3 NFs. This work may inspire the PEC application in other co-catalyst decorated systems.

Electrochemical performance of magnetic nanoparticle-decorated reduced graphene oxide (MRGO) in various aqueous electrolyte solutions

The objective of this work is twofold: (1) to improve the electrochemical performance of reduced graphene oxide (RGO) by decorating RGO sheets with magnetic nanoparticles (MNPs) and (2) to evaluate the electrochemical performance of RGO and MNP-decorated RGO (MRGO) in various aqueous electrolyte solutions (phosphate buffer solution (PBS) containing ferricyanide, PBS containing ferricyanide and KCl, Na2SO4, and KOH). The morphological and structural characteristics of solvothermal synthesized RGO and MRGO revealed the decoration of phase pure Fe3O4 nanoparticles on RGO sheets. In FC-PBS-KCl electrolyte solution, MRGO showed higher redox peak current (83.89 μA) and lower peak potential separation (0.11 V) at 50 mV s−1 scan rate compared with that in FC-PBS electrolyte solution. MRGO showed 15.5% higher peak current than that for the RGO in FC-PBS-KCl electrolyte solution. Moreover, the peak current for MRGO in FC-PBS-KCl was increased by 30% when compared with that in FC-PBS electrolyte solution. These results suggest that MRGO in FC-PBS-KCl electrolyte solution can be a good electron pathway between electrode and electrolyte solution for sensing applications. On the other hand, in both Na2SO4 and KOH electrolyte solution, RGO and MRGO showed supercapacitive behavior. In KOH, MRGO exhibited higher specific capacitance (180 Fg−1 at 3 A g−1) and superior cyclic stability (87% after 2000 cycles) compared with that in Na2SO4. MRGO showed 219% increase in specific capacitance than that of the RGO in KOH electrolyte solution. The superior electrochemical performance of MRGO compared with that of RGO is attributed to the synergistic effect of conductivity of RGO and redox activity of MNPs.

Photoelectrochemical reduction of CO2 using a TiO2 photoanode and a gas diffusion electrode modified with a metal phthalocyanine catalyst

The mass transport limitations encountered in classical H-cells for electrochemical CO2 reduction reaction (CO2RR) have spurred research in gas diffusion electrode (GDE) systems. However, current reports on CO2RR required large biases (anode potential vs. cathode potential > -2.0 V) for high current efficiencies. In this work, we combined a TiO2 photoanode and a GDE modified with a Co, Ni or Sn metal phthalocyanine (MPc) catalyst to reduce the external bias requirement for CO2RR. We found the Faradaic efficiencies and the selectivity of the photoelectrolysis products were influenced by (i) the metal cation (Ni, Co or Sn) coordinated to the phthalocyanine, (ii) the electrolyte temperature and concentration and (iii) the magnitude of the applied bias. In addition, analyzes of the voltage distributions between the TiO2 photoanode and the MPc-GDE revealed the current efficiency of the TiO2/MPc-GDE cell was limited predominantly by a high ohmic polarization loss at the TiO2 photoanode due to an excessive thickness of the TiO2 layer. The cathodic process at the MPc-GDE was governed by the activation energy of the electrode. The thickness of the TiO2 photoanode was subsequently optimized for higher current efficiency. The highest Faradaic efficiency for PEC CO2RR was obtained when a NiPc catalyst was utilized as the CO2RR catalyst and the optimum cell conditions were as follows: (i) a GDE electrolyte temperature of <11 °C, (ii) a GDE electrolyte concentration of >1 M aq. Na2SO4 electrolyte solution and (iii) a TiO2 oxidation time of 3 h. Using these optimized cell conditions and under UV illumination, the as-prepared TiO2/NiPc-GDE cell shows a notably high CO2RR Faradaic efficiency and selectivity for CO (at 98%) and at a lowest reported cell bias of 0.8 V (anode potential vs cathode potential). This work provides an improved understanding of the cell designs of a vapor-fed CO2RR reactor based on a TiO2/MPc-GDE photoelectrochemical system.

Synthesis, Characterizaiton of CuO nano-rod for Supercapacitor Applications

A novel approach solvothermal synthesis method has been utilized to prepare CuO nanorods for electrochemical capacitors. A new method of synthesis has been adopted for the synthesis of CuO nanostructures. Structural, morphological features of the prepared material were studied by XRD and SEM respectively. Electrochemical supercapacitive performances of the modified electrode material were also analyzed by electrochemical workstation in three-electrode system. This material found to exhibit pesudocapacitive behavior with high capacitance of 135.23 F/g at the prevalent density of 1 A/g in 1M Na2SO4 electrolyte solution, proving a suitable candidate electrode material for supercapacitor applications.

Synthesis, Characterizaiton of Cuo Nano-Rod for Supercapacitor Applications

A novel approach solvothermal synthesis method has been utilized to prepare CuO nanorods for electrochemical capacitors. A new method of synthesis has been adopted for the synthesis of CuO nanostructures. Structural, morphological features of the prepared material were studied by XRD and SEM respectively. Electrochemical supercapacitive performances of the modified electrode material were also analyzed by electrochemical workstation in three-electrode system. This material found to exhibit pesudocapacitive behavior with high capacitance of 135.23 F/g at the prevalent density of 1 A/g in 1M Na2SO4 electrolyte solution, proving a suitable candidate electrode material for supercapacitor applications.

MnOx thin film based electrodes: Role of surface point defects and structure towards extreme enhancement in specific capacitance

Manganese oxide (MnOx) is a low cost and environment-friendly electrode material for supercapacitors. Although most efforts have been devoted to increase the surface area of this material, the role of surface defects in different MnOx polymorphs towards improvement of its capacitance remains to be thoroughly investigated. In this paper, the results from electrodeposition of mesoporous MnOx thin film electrodes and the effect of rapid thermal annealing (RTA) on their electrochemical storage behavior are presented and discussed. X-ray photoelectron spectroscopy (XPS) analyses showed an increase of the Mn2+/Mn3+ ratio as well as hydroxyl group defects on the surface of the annealed electrodes. The as-deposited MnOx did not manifest any capacitance behavior in 1.0 M Na2SO4 electrolyte solution. However, after RTA treatment, the specific capacitance was tremendously enhanced. An areal capacitance as high as 110 mF cm−2 at 5 mV s−1 was recorded in 1.0 M Na2SO4 electrolyte with a capacitance retention of 74% after 5000 charge-discharge cycles. Furthermore, the RTA treatment of electrodes significantly decreased the charge transfer resistance value from 0.678 × 106 Ω for the pristine MnOx electrode to 39.13 Ω for the treated one. Based on structural and surface chemistry evolution of the MnO2 films after annealing, the electrochemical storage behavior of annealed MnOx is discussed.

Development of Copper Cobalt Sulfide with Cu : Co Ratio Variation on Carbon Cloth as an Efficient Electrode Material for the Oxygen Evolution Reaction

AbstractWhen designing a device for energy conversion, development of a highly active catalyst for OER (oxygen evolution reaction) reaction in alkaline medium is of utmost importance. For energy conversion, herein, we developed copper cobalt sulfide on carbon cloth (CC) using a simple and facile hydrothermal method. A vertically grown 2D sheet‐like structure of copper‐cobalt sulfide is observed using L‐cysteine as a sulfur source. An optimized ratio of copper(II) and cobalt(III) and the best sulfur source are found to boost the electrocatalytic activity of mixed metal thiospinel for OER. Several characterization techniques (XRD, Raman, FESEM, TEM, XPS, and ICP‐AES) were used to confirm phase purity, morphology, and composition of copper cobalt sulfides. We have established that 2D nanosheets of CuCo3Sz/CC exhibited superior electrocatalytic performance over bare RuO2 in 1.0 M KOH solution. It is observed that CuCo3Sz/CC need only 105 mV overpotential to generate 5 mA/cm2 current density. CuCo3Sz/CC is very stable and able to produce unaltered current density under an applied potential of 1.615 V vs. RHE for 48 h. Electrochemically active surface area calculation is performed for all catalysts to confirm higher electrocatalytic activity. The catalyst, CuCo3Sz/CC is used in a broad pH region using 0.5 M KOH, saline water, and 0.5 M Na2SO4 electrolyte solution to widen the applicability of water splitting. This work shows an avenue to develop active and durable electrocatalyst for OER without using any noble metal electrocatalyst.

Facile and controllable CTAB-assisted sonochemical synthesis of one-dimensional MnWO4 nanorods for supercapacitor application

A facile and controllable synthesis approach has been established to prepare unique one-dimensional MnWO4 nanorods via cost effective CTAB-assisted sonochemical method. The variations in structure and surface morphology of MnWO4 materials with concentration of CTAB template were examined systematically through various characterization techniques. MnWO4 prepared using high concentrations (0.003 M) of CTAB displays a uniform nanorod structure. Moreover, electrochemical features of all the MnWO4 materials were assessed using cyclic voltammetric (CV) and chronopotentiometric (CP) analyses. Interestingly, the MnWO4 nanorods exhibit an outstanding performance with significantly high specific capacitance of 247 Fg-1 at a scan rate of 5 mV s−1 and a good cycling stability with 90% retention of initial capacitance, even after 3000 continuous CV cycles at the high scan rate of 100 mV s−1 in an aqueous 1M Na2SO4 electrolyte solution. Correspondingly, the as synthesized MnWO4 materials (without calcination) exhibit the specific capacitance of 187 Fg-1 at a scan rate of 5 mVs−1 and cyclic stability analysis provides 81% of initial specific capacitance after 3000 cycles. These excellent electrochemical properties tend to formulate the possibility of utilising of calcined MnWO4 nanomaterials for advanced energy storage applications.