KCl Electrolyte Research Articles

Bendable tube-shaped supercapacitor based on reduced graphene oxide and Prussian blue coated carbon fiber yarns for energy storage

Carbon fiber yarns (CFY) are promising as a new type of flexible building blocks for the construction of flexible architectures for the energy storage applications. The main hurdle with CFY is how to make them high energy and power capable by using economically and environmentally viable materials. Here, we report reduced graphene oxide (rGO) and Prussian blue (PB) coated CFY, derived from a facile electrochemical process at room temperature for supercapacitor electrodes. The PB coated CFY and rGO coated CFY electrodes exhibit the excellent gravimetric capacitance of 339 F/g and 160.2 F/g, respectively, in aqueous KCl electrolyte in three-electrode cell configuration. When we coupled these electrodes inside the flexible plastic tube and separated by the electrolyte wet filter paper in order to construct flexible architecture, the resulting device delivers excellent specific energy of 52.1 Wh/kg and 26.5 Wh/kg with offering specific power of 3100 W/kg and 14400 W/kg respectively, under a wide operating potential of 1.8 V with excellent rate capability. The device shows high tolerance towards bending, and retained its efficiency to the capacitance after being bent at an angle of 360° for 200 bending cycles.

Multi-Layer Electrodes for Electrochemical Antifouling

One of key issues in navigation and marine technology is the biofouling of underwater surfaces. Ten thousand of Cargo vessels as well as smaller motorboats, yachts and even offshore installations are affected. Biofouling involves the biological settlement of organisms and its continuous growth forming complex layers of centimetre thickness. This process severely increases of docking periods, corrosion, roughness and mass. For ship hulls, this leads to a huge hydrodynamic drag and, thus, higher fuel consumption at a constant speed [1]. Different seas and oceanas have their unique biotopes demanding specialised requirements of protective coatings. Since the prohibition of tin-organic coatings in 2003 an environmentally friendly as well as universally effective coating for antifouling has not been found yet. Even state-of-the-art copper and biocidal containing varnishes have fallen into disrepute as they contain bioaccumulating substances [2-5]. However, the biocidal-free, electrochemical antifouling technology can be applied regardless for the specific naval environment. Therefore, this is a promising approach for coating protection of ships that pass many seas. The antifouling effect of this concept is based on electrochemically generated redox stresses by pole changing of the electrodes in controlled sequence of intervals which also leads to changes of the pH between 2 and 12 at the surface. Additionally, the antimicrobial effect of anodically generated chlorine, and thereby hypochlorite, is under discussion [6-8]. This technological approach requires large electrodes with a very homogenous electrically conductive coating. In this study, polyurea coatings become electrically conductive resulting in conductivities between 0.1 and 160 mS cm-1 by homogeneous admixing of graphite flakes. This opens up a way to large area electrodes which can be deposited by rolling and brushing. Smoothly grinded surfaces of the conductive lacquers are investigated by scanning electrochemical microscopy (SECM) in the feedback mode in an 0.1 M KCl electrolyte with 2 mM K3[Fe(CN)6] as mediator. The distribution of the current at tip of an ultramicroelectrode of Pt over the coated working electrode allows imaging of the topographic distribution of conductivity and electrolysis with resolution at the micrometer scale. In the substrate-generator/tip-collector (SG/TC) modus is shown, that the anodic oxidation of chloride to chlorine also at potentials E = 1.3 V in 1 M KCl at pH = 8 is accompanied by the anodic oxidation of hydroxide ions. Therefore, besides the inherent pH stress, both, chlorine species and reactive oxygen species, preferably hydroxyl radical and hydrogen peroxides, cause a disinfecting redox stress suppressing settlement and growth of marine organisms. Imaging of the painted working electrode by scanning electrochemical microscopy give detailed information about the corrosion at their surface both at polymer matrix and dispersed graphite particles. Based on paintable large-area electrodes sea water electrolysis takes place at low current densities between 0.05 and 0.2 mA cm-2and generates a pH- and redox stress at the surface. Adjusting the ratio of conductivities between an outer and an inner layer of the painted electrodes a homogeneous distribution of the current density can be achieved also at large area electrodes. These conductive graphite composite coatings based on polyurea show an outstanding electrochemical stability with extremely low swelling in sea water. The coatings are painted on steel plates pre-coated by an isolating primer and the test plates keep almost free of any settlement of marine organisms over 16 month, e.g. barnacles and mussel among others. Abbott, A.; Abel, P. D.; Arnold, D. W.; Milne, A. Sci Total Environ 2000, 258, p. 5.Tolosa, I.; Readman, J. W.; Blaevoet, A.; Ghilini, S.; Bartocci, J.; Horvat, M. Mar Pollut Bull 1996, 32, p. 335.Thomas, K. V.; Fileman, T. W.; Readman, J. W.; Waldock, M. J. Mar Pollut Bull 2001, 42, p. 677.Connelly, D. P.; Readman, J. W.; Knap, A. H.; Davies, J. Mar Pollut Bull 2001, 42, p. 409.Biselli, S.; Bester, K.; Huhnerfuss, H.; Fent, K. Mar Pollut Bull 2000, 40, p. 233.Nakasono, S.; Burgess, J. G.; Takahashi, K.; Koike, M.; Murayama, C.; Nakamura, S.; Matsunaga, T. Appl Environ Microb 1993, 59, p. 3757.Satpathy, K. K.; Mohanty, A. K. Biofouling and its Control in Seawater Cooled Power Plant Cooling Water System - A Review; Sciyo, 2010 S. 191.Stoodley, P.; deBeer, D.; LappinScott, H. M. Antimicrob Agents Ch 1997, 41, S. 1876.

Electrochemically synthesized mesoporous architecture of vanadium oxide on flexible stainless steel for high performance supercapacitor

Mesoporous architecture of vanadium oxide thin films were successfully synthesized on flexible stainless steel substrates [SS (1.5 × 5 cm, no- 304)] at 2.30 V deposition potential by potentiostatic electrodeposition technique using 0.007 M, 20 ml aqueous solution of vanadyl sulphate. Electrochemical properties of electrodeposited V2O5 electrodes were analyzed by cyclic voltammetry, chronopotentiometric charge discharge and electrochemical impedance in 1 M aqueous KCl electrolyte. The annealed vanadium oxide electrode (400 °C for 3 h) shows highest value of specific capacitance 608.94 F/g at 5 mV/sec in 1 M KCl. Charge discharge behavior exhibits high reversibility with specific energy 63.73 Wh/kg, specific power146.66 kW/kg and columbic efficiency (η) 94.97%. Impedance spectroscopy reveals capacitive behavior and gives combined internal resistance ~1.53 ohm.

Surface Redox Chemistry of Immobilized Nanodiamond: Effects of Particle Size and Electrochemical Environment

The size of the diamond particle is tailored to nanoscale (nanodiamond, ND), and the ND surface is engineered targeting specific (electrochemical and biological) applications. In this work, we investigated the complex surface redox chemistry of immobilized ND layer on conductive boron-doped diamond electrode with a broad experimental parameter space such as particle size (nano versus micron), scan rate, pH (cationic/acidic versus anionic/basic), electrolyte KCl concentration (four orders of magnitude), and redox agents (neutral and ionic). We reported on the significant enhancement of ionic currents while recording reversible oxidation of neutral ferrocene methanol (FcMeOH) by almost one order of magnitude than traditional potassium ferricyanide (K3Fe(CN)6) redox agent. The current enhancement is inversely related to ND particle diameter in the following order: 1 μm << 1000 nm < 100 nm < 10 nm ≤ 5 nm < 2 nm. We attribute the current enhancement to concurrent electrocatalytic processes, i.e. the electron transfer between redox probes and electroactive surface functional (e.g. hydroxyl, carboxyl, epoxy) moieties and the electron transfer mediated by adsorbed FcMeOH+ (or Fe(CN)63+) ions onto ND surface. The first process is pH dependent since it depends upon ND surface functionalities for which the electron transfer is coupled to proton transfer. The adsorption mediated process is observed most apparently at slower scan rates owing to self-exchange between adsorbed FcMeOH+ ions and FcMeOH redox agent molecules in diffusion-limited bulk electrolyte solution. Alternatively, it is hypothesized that the surface functionality and defect sites (sp2-bonded C shell and unsaturated bonds) give rise to surface electronic states with energies within the band gap (midgap states) in undoped ND. These surface states serve as electron donors (and acceptors) depending upon their bonding (and antibonding) character and, therefore, they can support electrocatalytic redox processes in the presence of specific redox-active molecules via feedback mechanism. Apparently, FcMeOH+ tended to have electrostatic affinity for negatively charged ND surface functionalities, corroborated by present experiments. We also attempted to study biocatalytic process using model metalloprotein (cytochrome c; Cyt c) immobilized on ND particles for investigating interfacial electron transfer kinetics and compared with those of functionalized graphene (graphene oxide; GO and reduced GO). The findings are discussed in terms of interplay of sp3-bonded C (ND core) and sp2-bonded C (ND shell and graphene-based systems).

Large Rectification Effect of Single Graphene Nanopore Supported by PET Membrane.

Graphene is an ideal candidate for the development of solid state nanopores due to its thickness at the atomic scale and its high chemical and mechanical stabilities. A facile method was adopted to prepare single graphene nanopore supported by PET membrane (G/PET nanopore) within the three steps assisted by the swift heavy ion irradiation and asymmetric etching technology. The inversion of the ion rectification effect was confirmed in G/PET nanopore while comparing with bare PET nanopore in KCl electrolyte solution. By modifying the wall charge state of PET conical nanopore with hydrochloric acid from negative to positive, the ion rectification effect of G/PET nanopore was found to be greatly enhanced and the large rectification ratio up to 190 was obtained during this work. Moreover, the high ionic flux and high ion separation efficiency was also observed in the G/PET nanopore system. By comparing the "on" and "off" state conductance of G/PET nanopore while immersed in the solution with pH value lower than the isoelectric point of the etched PET (IEP, pH = 3.8), the voltage dependence of the off conductance was established and it was confirmed that the large rectification effect was strongly dependent on the particularly low off conductance at higher applied voltage.

Comparative study of N719 dye on two different photo-anodes

Nano-composites of TiO2 and ZnO were successfully prepared using the doctor blade application and high temperature sintering on indium-doped tin oxide (ITO) glass substrate. They were used as efficient photo anode in high performance dye-sensitized solar cells (DSSCs) assembled with N719 dye. The high-density frameworks of TiO2 and ZnO were synthesized on separate ITO conducting glass using a facile and cost-effective two-step approach to compare the output efficiency. We report on the interfacial boundary relationships, charge – collection conversion efficiency and I-V characteristics of the DSSCs with different electrolytes. The TiO2 photo anode demonstrated an enhanced solar-to-electrical energy conversion of approximately 5.41 % with KCl electrolyte which was far less than that of a ZnO photo anode with KCl electrolyte which had about 21 % increase under conditions of 1.5 AM. Because of the enhanced solar energy conversion of the ZnO photo anode, l.arboreus with KI sensitizer records 9.78 % is a promising candidate for large manufacture of high performance DSSCs modules.

Size control of monodisperse silica particles by modified Stöber method

ABSTRACTMonodispersed silica spheres were prepared by an effective method, which an ethanolic solution of tetraethyl orthosilicate (TEOS) was continuously supplied to the reaction mixture containing KCl electrolyte, water, TEOS, ethanol and ammonia. The particle size of the silica spheres ranged from 2.0 to 4.5 µm. In addition, the effects of reaction conditions such as temperature and amount of ammonia on microsphere morphology were studied.

Evidence of Ion-Pairing in Cationic Brushes from Evaluation of Brush Charging and Structure by Electrokinetic and Surface Conductivity Analysis

Strong cationic poly(2-(methacryloyloxy)ethyltrimethylammonium chloride) (PMETAC) brushes are widely employed as platform for studying fundamental physicochemical properties of permanently charged polymers at interfaces. We report here a detailed analysis of the structure, interfacial and bulk charging of PMETAC brushes over a broad range of pH values and salt concentrations (pH 2.5–9.5, 0.01–10 mM KCl electrolyte). Streaming current and surface conductivity measurements were quantitatively analyzed on the basis of a recently developed theory for electrohydrodynamics at diffuse soft interfaces under lateral flow conditions taking into account ion pairing at low salt concentrations. In addition, the effects of different chaotropic anions on brush charge and thickness were deciphered from interpretation of surface conductivity data collected in 1 mM KNO3, KI, and KClO4 electrolytes. In combination, confrontation between theory and experiments reveals the existence of a PMETAC segment density gradient at the...

Comparison of current-voltage characteristics in solutions of the NaCl and KCl electrolytes measured by means of stationary and pulse schemes

Comparison of current-voltage characteristics in solutions of the NaCl and KCl electrolytes measured by means of stationary and pulse schemes

Efficient Solar-Induced Photoelectrochemical Response Using Coupling Semiconductor TiO₂-ZnO Nanorod Film.

Efficient solar driven photoelectrochemical (PEC) response by enhancing charge separation has attracted great interest in the hydrogen generation application. The formation of one-dimensional ZnO nanorod structure without bundling is essential for high efficiency in PEC response. In this present research work, ZnO nanorod with an average 500 nm in length and average diameter of about 75 nm was successfully formed via electrodeposition method in 0.05 mM ZnCl2 and 0.1 M KCl electrolyte at 1 V for 60 min under 70 °C condition. Continuous efforts have been exerted to further improve the solar driven PEC response by incorporating an optimum content of TiO2 into ZnO nanorod using dip-coating technique. It was found that 0.25 at % of TiO2 loaded on ZnO nanorod film demonstrated a maximum photocurrent density of 19.78 mA/cm2 (with V vs. Ag/AgCl) under UV illumination and 14.75 mA/cm2 (with V vs. Ag/AgCl) under solar illumination with photoconversion efficiency ~2.9% (UV illumination) and ~4.3% (solar illumination). This performance was approximately 3–4 times higher than ZnO film itself. An enhancement of photocurrent density and photoconversion efficiency occurred due to the sufficient Ti element within TiO2-ZnO nanorod film, which acted as an effective mediator to trap the photo-induced electrons and minimize the recombination of charge carriers. Besides, phenomenon of charge-separation effect at type-II band alignment of Zn and Ti could further enhance the charge carrier transportation during illumination.

Synthesis, Characterization and Electrochemical Sensing of Tb2O3 Nanotubes

One dimensional terbium oxide (Tb2O3) nanotubes have been synthesized by using surfactant free precipitation method and investigated its non-enzymatic electrochemical detection for hydrogen peroxide (H2O2). The structural analysis and x-ray diffraction data confirmed the formation of cubic phase Tb2O3 in the synthesized Tb2O3 nanotubes. The optical property of the synthesized product was investigated by ultraviolet spectroscopy and photoluminescence (PL) studies. The PL spectrum of Tb2O3 nanotubes exhibited a strong green luminescence corresponding to 5D4 → 7F5 transition of Tb3+ ions. The non-enzymatic hydrogen peroxide (H2O2) sensing of Tb2O3 nanotubes/carbon paper modified electrodes in 1 M KCl electrolyte was carried out using cyclic voltammetry and amperometric (i–t) analysis. The enhanced electrocatalytic behavior was observed for Tb2O3 nanotubes with an excellent sensitivity of 875 μA mM−1 cm−2, linear ranges of 0.5–5 mM and a low detection limit of 5 μM.

Electrochemical noise and impedance of Au electrode/electrolyte interfaces enabling extracellular detection of glioma cell populations.

Microelectrode arrays (MEA) record extracellular local field potentials of cells adhered to the electrodes. A disadvantage is the limited signal-to-noise ratio. The state-of-the-art background noise level is about 10 μVpp. Furthermore, in MEAs low frequency events are filtered out. Here, we quantitatively analyze Au electrode/electrolyte interfaces with impedance spectroscopy and noise measurements. The equivalent circuit is the charge transfer resistance in parallel with a constant phase element that describes the double layer capacitance, in series with a spreading resistance. This equivalent circuit leads to a Maxwell-Wagner relaxation frequency, the value of which is determined as a function of electrode area and molarity of an aqueous KCl electrolyte solution. The electrochemical voltage and current noise is measured as a function of electrode area and frequency and follow unambiguously from the measured impedance. By using large area electrodes the noise floor can be as low as 0.3 μVpp. The resulting high sensitivity is demonstrated by the extracellular detection of C6 glioma cell populations. Their minute electrical activity can be clearly detected at a frequency below about 10 Hz, which shows that the methodology can be used to monitor slow cooperative biological signals in cell populations.

Layered MoS2/PPy nanotube composites with enhanced performance for supercapacitors

Using polypyrrole (PPy) nanotubes as the substrate, the layered molybdenum disulfide (MoS2) nanosheets were wrapped on PPy nanotubes to form MoS2/PPy nanocomposites by a hydrothermal reaction. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that MoS2 nanosheets coated uniformly on the surface of PPy nanotubes owing to the electrostatic force. The specific capacitance of the MoS2/PPy nanocomposites was high up to 307.5 F g−1, much higher than that of the pure PPy with specific capacitance of 106.3 F g−1 and MoS2 with specific capacitance of 138.5 F g−1 at a current density of 1.0 A g−1 in 1 M KCl electrolyte. And the special structure of MoS2/PPy nanocomposites electrode reduces the deformation during the charge–discharge process and thus improves the rate stability and electrochemical cycling stability of the electrode significantly. The specific capacitance retains 96.47 % after 1000 charge–discharge processes which provides potential as supercapacitors.

Dielectric relaxation of suspension of polystyrene-poly (butyl acrylate) (PS-PBA) particles and dielectric model analysis: Electrical and electrokinetic parameters

Dielectric behaviors of suspensions of monodisperse polystyrene-poly (butyl acrylate) (PS-PBA) particles with the radius of 120nm were thoroughly investigated in the frequency range of 40Hz to 110MHz. Two remarkable dielectric relaxations were simultaneously observed, and the well-known Einstein equation and Grosse theory were employed to analysis the relaxation mechanism. Meanwhile, Dukhin-Shilov theory about the thin double layer of colloid dispersion was employed to verify the effects of volume fraction and KCl electrolyte concentration on dielectric parameters of DRS. The results showed that the changing trend of relaxation frequencies and dielectric increments from experimental data with KCl concentration and volume fraction was well consistent with the prediction of the wide-range DRS of Dukhin-Shilov theory. In addition, the reasonable phase parameters (εp,κp,εa,κaandϕ) were calculated by Hanai theory on the basis of the suggested dielectric model. Finally, the interfacial electrical parameters (λ,σ,ζ) of PS-PBA microspheres dispersed in different concentrations of KCl electrolyte solution were obtained by electrodynamics equations about interface on the basis of dielectric analysis. More importantly, the calculated value of ζ well agreed with the value (- 48.8mV) measured by Zeta potential analyzer, thus the result proved that DRS was a feasible method to investigate the interfacial electrical parameters of disperse system in a non-intrusive way.

Glycine-assisted aqueous suspension of reduced graphene oxide/Ag nanocomposite via in situ reduction at room temperature: synthesis and electroactivity behavior

Here we reported a mild, efficient and environmentally method for the preparation of a stable aqueous suspension of reduced graphene oxide (rGO)/Ag nanocomposite. Nanocomposite was synthesized based on glycine (Gly) modified Ag nanoparticles (MAg NPs) at room temperature, which Gly acted as both a stabilizer of Ag NPs and a reducing agent for conversion of GO to rGO. The results confirmed the presence of Ag NPs in rGO/Ag nanocomposite and also the successful reduction of GO sheets without use of reducer. Finally, cyclic voltammetry showed immobilized nanocomposite on the surface of a glassy carbon (GC) electrode has good electroactivity in 1M KCl electrolyte.

Determination of Sorption Coefficient of Phosphorus Applied for Sugarcane Production in Southwestern Florida.

Phosphorus is among the essential nutrients applied to sugarcane ( L.) fields in the form of a fertilizer mixture (N, P, and K) in southwestern Florida. Sorption coefficient is used for modeling P movement, and in this study, we hypothesized that the sorption coefficient determined using fertilizer mixture (N, P, and K) will be significantly different from values determined using KCl and CaCl, the electrolytes most commonly used for conducting sorption experiments. Supporting electrolytes, 0.01 mol L KCl, 0.005 mol L CaCl, deionized (DI) water, simulated Florida rain, and fertilizer mixture prepared in Florida rain were used to characterize P sorption. Immokalee (Sandy, siliceous, hyperthermic Arenic Alaquods) and Margate (Sandy, siliceous hyperthermic Mollic Psammaquents) are the dominant mineral soils used for sugarcane production in southwestern Florida; we used the A and B horizons of Margate soil and the A and B horizons of the Immokalee soil for sorption experiments in this study. Freundlich sorption isotherms described P sorption data. The Freundlich sorption isotherm coefficients followed the trend 0.005 mol L CaCl > 0.01 mol L KCl ≈ fertilizer mixture > simulated Florida rain ≈ DI water. Sorption coefficients were used for modeling P movement with HYDRUS 1D; similar P results were obtained with the 0.01 mol L KCl and fertilizer mixture electrolyte treatments. The sorption coefficient for DI water and simulated Florida rain overpredicted P movement. The P sorption data showed the importance of choosing the appropriate electrolyte for conducting experiments based on the composition of fertilizer.

Crystallographically-Oriented Macropores in Multi-Crystalline Zn

In this abstract we report on the electrochemical formation of crystallographically-oriented macropores in multicrystalline Zn sheets. The formation of macropores by electrochemical etching is well-known from silicon and other semiconductors like InP or GaAs as model systems for the growth of crystallographic pores. Besides semiconductors pores have also been formed in specific metals like Al and Ti, where the resulting pore walls turned into metal oxides. The substrate for the growth of crystallographic pores in Zn is a commercially available multicrystalline Zn sheet with a thickness of 0.1 mm and a purity of 99.95 %. The hardness degree is as-rolled. The pores are grown in a self-organized manner without any pre-structuring of the Zn substrate in pulsed-potential process in an adopted aqueous KCl electrolyte. The crystallographic nature of the pores grown is easily detectable due to the multicrystalline Zn substrate, see Fig. 1. Here, pores form pore domains typically in the dimensions of the specific grain they are growing in. Inside a pore domain the neighboring pores grow parallel to each other into the depth - see the inset of Fig.1 - under a defined angle depending on the crystal orientation of the grain. These angles can vary from perpendicular to almost parallel to the sheet surface normal. The pores exhibit a wide diameter distribution from around 100 nm up to several micrometers. This vast diameter range is a direct result of the pulsed-potential etching process causing frequent nucleations of new pores on the Zn surface. The microscale diameter pores originate from potential pulses at the beginning of the etching process. The shape of the pore openings transforms during the etching process. Young pores, i.e. late nucleated pores, typically exhibit a distorted hexagonal pore opening transforming into rhomboidal with continued etching time. This is a direct consequence of the design of the etching process itself, which is separated into a cathodic surface passivation process and an anodic dissolution process. With increasing pore length the pore wall passivation near the pore openings weakens resulting in a change in shape and a broadening of the pore openings. A renucleation of pores from the pore walls is also observed as one of the characteristic features of crystallographic pores found in III-V semiconductors. XRD measurements of the porosified and untreated Zn sample show only peaks that can be assigned to crystalline Zn in its typical hcp crystal structure. The shape of the Zn peaks indicates rather large coherently scattering areas and thus, rather big Zn grain sizes. No additional peaks or amorphous halos appeared in the diffractogram that might be associated with ZnO, etc. EDX elemental mapping performed on the pore walls of pores growing into Zn under a low angle with respect to the sheet surface normal indicates that the pore walls consist of Zn with a native oxide coverage. These Zn pore structures form a mechanical interlocking surface structure that could be employed to solve the common problem of poorly adhering paint layers on Zn plated metal surfaces. Fig.1 SEM top view on the macroporous Zn surface with multiple pore domains, inset: high magnification of single pores inside a pore domain. Figure 1

Crystallographically-Oriented Macropores in Multi-Crystalline Zn

This paper presents the self-organized growth of crystallographically-oriented macropores in multicrystalline Zn sheets by pulsed-potential electrochemical etching in an environmentally friendly aqueous KCl electrolyte. The resulting pores show very high similarity to crystallographically-oriented pores found in III-V semiconductors with respect to branching and intersection of pores. In contrast to pores in other metals like Ti with amorphous TiO2 pore walls, the pore walls in Zn entirely consist of metallic Zn. These pores in multicrystalline Zn are perfectly suitable for mechanical interlocking with polymers since the pores grow under various angles to the sheet surface. All pores grow in <0001> directions with side branching pores in [-12-10] and in [1-210] direction allowing for a good mechanical interlocking to polymers, i.e. they act perfectly as hooks forming a rigid connection between the Zn sheet and the polymer solving the well-known problem of poor adhesion of polymers and paint on Zn surfaces.

Capacitance enhancement in supercapacitors by incorporating ultra-long hydrated vanadium-oxide nanobelts into graphene

The oriented synthesis of high-performance nanobelt/graphene hybrids remains a challenge by one-step environmentally friendly process for supercapacitors. Here, PEG-6000 manipulation was employed to facilitate ultra-long V2O5·0.5H2O nanobelts on surface of reduced graphene oxide (rGO). As a result, due to faster and efficient electron transfer and collection, V2O5·0.5H2O/rGO hybrid (rGO: 5 wt%–50 wt%) significantly enhances electrochemical capacitance for supercapacitors. Especially, introduction of 50 wt% rGO in the hybrid (denoted as 50 wt% rGO-V) exhibits a high capacitance of 649 F g−1 at a scan rate of 5 mV s−1 in a neutral KCl electrolyte. On the other hand, the hybrid material shows a high-rate capacitance of 160 F g−1 at a current density of 1 A g−1. Additionally, capacitance retention of 93% was obtained after 600 cycles, implying excellent cycling stability in the 50 wt% rGO-V hybrid. This study is beneficial to understand synergetic effects in V2O5·0.5H2O/rGO hybrid materials and even useful for oriented synthesis of hybrid materials in other energy storage devices.

Structural and electrical properties of tracks of heavy ions in polyethylene terephthalate and mica

An image of the entrance of high-energy ions of krypton, xenon, and bismuth on the surface of polyethylene terephthalate (PET) and mica is obtained. It is shown that in both cases the tracks have the appearance of protuberances. The formation of protuberances is associated with the destruction of material in the region of the track, the formation of amorphous structure, and the removal of low-molecular-weight radiolysis products as gaseous substances. Storage of the irradiated PET samples in water and a weak alkaline solution for several hours changes the surface topography due to hydrolysis of the material and the removal of radiolysis products into the solution. The kinetics of etching tracks in a weak alkaline solution and the formation of pores are studied. The stream function, electrical resistance, and permeability of the tracks in KCl, LiCl, MgCl2, and BaCl2 electrolytes are measured. The surface charge of the tracks is calculated from these values.