Electric Layer Research Articles

Bipolar electrokinetic dehydration of wood by electro-osmosis of various breeds

In the article, the mechanism of electrokinetic’s dewatering of wood - electroosmosis is considered. Models of a structure of a double electric layer are considered. The electrokinetic way of wood dewatering is the most effective method. Its energy intensity is minimal. In given article results of experiments, bipolar electrokinetic’s dewatering of wood of various species of wood is considered. The bipolar expiration of a liquid from wood is observed for use as a material of the anode of the titan, aluminum, tin, lead and the alloys containing these materials. Most effectively wood dewatering is made across fibers. The speed of wood dewatering depends on intensity is established.

OCCURRENCE OF ACCELERATING FIELD, FORMATION AND DYNAMICS OF RELATIVISTIC ELECTRON BEAM NEAR JUPITER

The possible dynamics of the electron beam, formed in the vicinity of Io, the natural satellite of Jupiter, and injected toward Jupiter, has been investigated analytically. When a beam penetrates the Jupiter plasma to a certain depth, the beam-plasma instability can be developed. In this case, the distribution function of electrons is expanded additionally by excited oscillations. These electrons, when their energy is of order of a required certain value, cause UV polar light. For closing of a current, the formation of a double electric layer is necessary. The necessary parameters and conditions for the formation of a double layer with a large jump of an electric potential at a certain height have been formulated, its properties, stability, behavior over time and beam reflection in its field for closing of a current have been described. Reflection of the beam can lead to its vortex dynamics.

Carbon materials as a cathode for aluminum-ion battery

Activated carbon and fine-dispersed flake and spherical graphite were investigated as cathode materials for an aluminum-ion battery with an electrolyte of 1-ethyl-3-methylimidazolium chloride/AlCl3 (1:2). Cyclic voltammograms and the discharge curves for the activated carbon is fundamentally different from ones for graphite. It is assumed that the mechanism of operation of the activated carbon is based on the charging of the double electric layer, in contrast to graphite, where the main mechanism is the intercalation of the electrolyte ions into the crystal lattice. Specific capacity achieved 117mAh/g for activated carbon and 59 mAh/g for graphite (at 2,5V and 75mA/g)

Роль зарядового состояния поверхностных атомов металлической подложки в допировании квазисвободного графена

AbstractTo determine the effect of a metal substrate on the electronic state of quasi-free-standing graphene, a simple model taking into account the presence of the double electric layer on the metal surface is proposed. The arising electrostatic field shifts the Dirac point of graphene, which leads to its doping. An analytical expression for the charge of graphene atoms is obtained. Numerical estimations are made for (111) faces of Cu, Ag, Au, and Pt. The agreement of the obtained estimations with the available results of numerical calculations is discussed.

Negativni joni i njihova uloga u razvoju nauke i tehnologije

Negative ions are formed in the process of the interaction between the electron with the integrated electric dipole moment and the induced electric dipole moment due to polarization. In the continual regime, at orbital velocity, the emission of negative ions from the surface of the heat shielding coating leads to the formation of a double electric layer with a very dense plasma while at the escape velocity the same emission of negative ions creates an explosive character of burning of the heat shielding coating. In the free molecular flow regime, the emission of negative ions results in intense violet-blue glow while high positive potentials are induced on the surface of an aircraft. In nanotechnologies, the ionization of negative ions determines the parameters of vacuum arc discharge. Negative ions participate in the formation of an electrostatic machine in the human body.

Model and mechanism of carbon nanotube stabilization with plasticizer

Mechanism of stabilization of carbon nanotube (CNT) water suspension with plasticizer based on sulfated naphthalene formaldehyde resins is proposed in this article. CNT stabilization is achieved at the expense of fixing plasticizer group on the nanoparticle surface. Nonpolar part of plasticizer provides the formation of high-viscosity streak between CNTs particles and dispersion medium, and polar part provides the formation of double electrical layer, that supports formation of CNT micelle. Model of carbon nanotube micelle is described. It is determined that the conducting of ultrasonic dispersion of CNTs water suspensions with plasticizer based on sulfated naphthalene formaldehyde resins provides stability of CNTs suspensions for 7 and more days. Optimal options of ultrasonic effect are identified. It is shown that CNT suspension stabilized with sulfated naphthalene formaldehyde evenly apportion in volume of cement system in conclusion of the adding them to composition of cement paste. This distribution helps with obtaining cement stone with high exploitative properties.

In Ukrainian

The adsorption of adenine nucleotides with different phosphate chains from aqueous solutions onto nanocrystalline ceria surface was investigated. The adsorption dependences of pH and ionic strength are interpreted in terms of surface complexation theory.  The equilibrium reaction constants of  the formation of outer-sphere electrostatic complexes are calculated with using basic Stern model for double electric layer.

KINETICS OF CORROSION OF STEEL St3 IN PO-6СT FOAMING AGENT FOR FIRE EXTINGUISHING. ELECTROCHEMICAL INVESTIGATION

Foaming agents for extinguishing fires are to be stored in a concentrated form. Storage of concentrate in St3 steel containers is allowed. However, this metal can be corroded, which damages the storage tanks, and corrosion products of steel reduce the quality of the foaming agent. The kinetics of metal corrosion depends on the type of foaming agent and the temperature storage conditions. In this study, the corrosion behavior of St3 steel in commercial concentrate of the PO-6CT foam for extinguishing fires was studied by electrochemical methods (potentiometry, voltammetry, electrochemical impedance spectroscopy) at 27±1°С. It was found that during the testing period, which lasted for 6 weeks, the corrosion potential of steel began to undergo sharp fluctuations, but its value was generally negative than the initial value. The greatest changes in the impedance of the steel sample during the corrosion process occur in the first two weeks of contact with the corrosive medium. An equivalent circuit, which takes into account the two time constants was used to interpret the impedance data of the corrosion process which was occurred under the porous layer of corrosion products. It is shown, the charge transfer resistance (Rct) between the corrosive metal and corrosion products, the capacity of the double electrical layer (Cdl) and the electrolyte resistance in the pores of the corrosion products layer (Rpo) highly increase during this period. Subsequently, the Rct is decreased and stabilized at a level 3 times lower than the original value. The properties of the metal/electrolyte interface were stabilized, but the Cdl value and the Rpo values are increased by 5 times and by 10 times, respectively. This indicates a high degree of the surface rust and a stable state of the corrosion products layer. Polarization studies have shown that the anodic and cathodic polarization curves have a Tafel slope equals to 0.147 V and 0.187 V, respectively. This is due to the presence of an oxide-hydroxide film on the electrode surface. The calculated value of the mass index of corrosion rate is 2.46×10-8 kg×m-2×s-1. Thus, the experiment showed that the St3 corrosion proceeds with activation control of the process rate. The corrosive behavior of St3 in the PO-6CT foaming agent for fire extinguishing is a consequence of the physicochemical features of this system. Primary corrosion products of steel St3 (Fe+2 ions) can be readily oxidized to Fe+3 by dissolved oxygen of air, and Fe+3 ions undergo hydrolysis, which leads to an increase in the acidity of the foaming agent and, correspondingly, an increase in its corrosive activity.Forcitation:Grishina E.P., Kudryakova N.O., Predein A.N., Belyaev S.V. Kinetics of corrosion of steel St3 in PO-6СT foaming agent for fire extinguishing. electrochemical investigation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N1. P. 30-36

THE INFLUENCE OF DOUBLE ELECTRICAL LAYERS IN THE "METAL-ELECTROLYTE-POLYMER" FRICTION PAIR ON ITS ENERGY-LOADING (PART ONE)

The materials of the article illustrate the estimation of the energy loading of a metal friction element in the metal-electrolyte-polymer friction pair while forming various types of double electrical layers with the release of its thermal stabilization state. The energy loading of the contact spots of the microprotrusions of the friction pairs of braking devices depends to a large extent on the electrical, thermal and chemical fields that are of a different nature to an allowable temperature and are above the surface layers of the polymer patch. The latter is significantlyinfluenced by double electrical layers that are formed at the boundaries of the phases «metal-metal», «metal-polymer», «metal-semiconductor», «semiconductor-semiconductor» and «metal-electrolyte». When two electrically conducting phases come into contact with electrothermomechanical friction, a difference in electrical potentials arises, which is due to the formation of a double electric layer, that is an asymmetric distribution of charged particles near the phase boundary. The structure of the double electric layer does not matter for the magnitude of the reversible electrode potential, which is determined by the variation of the isobaric-isothermal potential of the corresponding electrochemical reaction. At the same time, the structure of the double electric layer plays an important role in the kinetics of electrical processes, including the kinetics of the ion exchange under equilibrium conditions, characterizing the intensity of this exchange, and as a consequence, in the occurrence of the thermal stabilization state of the metallic friction element. Thus, the classical approach to the processes of the double electric layer in a «metal-electrolyte-polymer» pair is illustrated, without taking into account the complex heat exchange to which the metal friction element of the braking devices is exposed.

Venus: A Low-Latency, Low-Loss 3-D Hybrid Network-on-Chip for Kilocore Systems

Network on chip (NoC) with more than 1000 cores is anticipated to meet the requirements of exascale computing in the foreseeable future. As latency is one of the most critical metrics to evaluate performance for kilocore-chip, researchers recently proposed optical networks on chip (ONoCs) with multiwavelength to achieve low latency. Nevertheless, with networks scaling to kilocores and too many wavelengths used, waveguide crossings loss and microring resonators (MRs) pass-by loss on the critical path are increased considerably. In this paper, we propose Venus, a three-dimensional NoC architecture with multiple photonic and electrical layers. By using space division multiplexing and hybrid wavelength assignments method, Venus possesses the following two features: 1) Each core can communicate with any other one in one hop and any two clusters in different subnets can communicate with each other without any blocking, thus reducing latency greatly; and 2) the number of waveguide crossings and also the MRs passed by on the critical path is reduced, thus saving energy consumption considerably. Architectures based on 64-core, 512-core, and 1024-core are simulated respectively. Evaluation results of different synthetic traffic patterns and real applications demonstrate that Venus significantly reduces the end-to-end latency and worst case loss compared to previous proposals.

Study of gelatin as biodegradable shale hydration inhibitor

In order to develop a biodegradable and efficient shale inhibitor, gelatin, a biodegradable amino polymer, was introduced as a potential shale inhibitor. The inhibitive properties were evaluated by linear swelling test, hot-rolling recovery test and montmorillonite (MMT) plate soaking test. The results showed that the inhibition of gelatin was better than other common inhibitors. The inhibitive mechanism of gelatin was also investigated via a variety of characterization methods. First of all, gelatin was adsorbed on MMT particles through electrostatic interactions and hydrogen bonds. Then, the negative charge on MMT particles was neutralized and the double electrical layers were suppressed. For the adsorbed gelatin molecules, only a few molecules entered the interlayer space and expelled water. Meanwhile, the main part of gelatin was strongly adsorbed on the surface of MMT particles and formed a polymer film, which made clay surface more hydrophobic. Thus, the polymer formed an effective shield to prevent the invasion of water. Finally, the MMT layers were compressed together in a form of thicker and larger agglomerations and the hydration was well inhibited.

Investigation of Deposits in Channels of Panels of a Heat-Transfer Agent

An analysis of the behavior of nanosized colloidal particles in a supersaturated solution made it possible to substantiate the possibility of increasing the heat-transfer efficiency in a heat exchanger during magnetic treatment of a heat-transfer agent. A model is proposed to weaken the scale during magnetic treatment of a water stream. A colloidal solution is shown to decrease its stability—the coagulation of colloidal particles begins—because of the deformation of the double electrical layer. As a result of increasing the effective radius of curvature of nanoparticles, the solution becomes strongly supersaturated with respect to forming aggregates, which accelerates the solidification of dissolved salts on them. The influence of the interfacial layer of nanoobjects decreases the energy of formation of critical nuclei (size effect) and their sizes. Since coagulation tends to decrease the concentration of critical nuclei in the solution, their loss should be compensated via the homogeneous generation of new nuclei. As a result, the concentration of suspended particles increases additionally and the antiscale effect is enhanced. The solidification flux of dissolved salts is shown to deposit mainly on suspended nanoparticles due to an increase in their total surface area and to the fact that the coefficient of mass transfer to suspension is higher than that to the wall by four orders of magnitude. The mathematical model constructed on the basis of the detected set of physical processes can be used to perform quantitative estimates of the antiscale effect in real power plants.

Mesoscopic theory of percolation currents associated with quantitative description of VAGs: Confirmation on real data

The general mesoscopic theory pretending on the quantitative description of the interfacial surface and the self-similar structure of the double electric layer in the vicinity of solid electrodes is suggested. It takes into account the fact that the fractal dimension can be complex and depends on the applied potential. In the frame of the suggested theory, the fitting function pretending on description of the VAGs was found. It was applied for the fitting of original experimental data related to detection of the Cd+ ions in different concentrations in the KCl solution. The assumptions and possible applications of the suggested theory to description of other measured data are discussed.

How Indium Nitride Senses Water

The unique electronic band structure of indium nitride InN, part of the industrially significant III-N class of semiconductors, offers charge transport properties with great application potential due to its robust n-type conductivity. Here, we explore the water sensing mechanism of InN thin films. Using angle-resolved photoemission spectroscopy, core level spectroscopy, and theory, we derive the charge carrier density and electrical potential of a two-dimensional electron gas, 2DEG, at the InN surface and monitor its electronic properties upon in situ modulation of adsorbed water. An electric dipole layer formed by water molecules raises the surface potential and accumulates charge in the 2DEG, enhancing surface conductivity. Our intuitive model provides a novel route toward understanding the water sensing mechanism in InN and, more generally, for understanding sensing material systems beyond InN.

Mathematical modeling of solution deionization by sorption on aerogel electrodes

The mathematical modeling is used to study the dynamics of solution deionization by sorption on aerogel electrodes. The matter transport by solution flow, diffusion, and sorption in pores are simulated. Several models are proposed to describe the phenomenon with different degree of approximation. Problems arising in numerical computing and ways to solve them are described. It is shown that at low solution concentrations and a small pore size the effect of electro-sorption is not reduced to the formation of a double electric layer on the pore surface, which uptakes ions from the solution. In addition to the formation of this layer distributed ionic charge is accumulated all over the pore space. The dependence of the effective diffusion coefficient inside the porous electrode on the ion concentration is found. Examples of calculating the deionization process at one-cycle and multi-cycle sorption are given.

On Diagnostics of Double Electric Layer in the Zone of Metal–Polymer Adhesion Contact Using the Positron-Annihilation-Probe Method

Application of the positron-annihilation-probe technique for nondestructive diagnostics of the double electric layer (DEL) at the polymer–metal interface and, hence, of the electric component of polymer adhesion to the metal is described. Separated curves of angular correlation of positron-annihilation radiation (ACPAR) for metal, polymer, and metal with a polymer layer allow detecting the presence of a strong electric field of a DEL at the nickel–epoxy-resin interface. The value of the DEL potential is determined to be 15 keV. The method of a positron-annihilation probe allows identifying the presence of a DEL on the internal interfaces of materials and estimating its energy parameters so as to correctly reflect the value of the contribution of the electrostatic component to the interphase interaction.

Preparation and Characterization of Efficient Flame-Retardant and Thermostability Two-Component Aqueous Varnish Coatings

A method to prepare efficient flame-retardant two-component waterborne polyurethane coatings by combining polyepichlorohydrin, polypropylene glycol, isocyanate, chain-extender and curing agent was developed. The structures and properties of latexes and films were determined by grain size, viscosity, FTIR, differential scanning calorimeter, mechanical properties, thermogravimetry, flame-retardant and applicant measurements. The results illustrated that the more the hydrated double electric layer of two-component varnish coatings latex particles was, the better the resulting mechanical and chemical stability was. The grain size increased and viscosity decreased as stoichiometric ratio of –OH to –NCO became larger. The lower T gs and higher T gh were attributed to the polar extender which hindered aggregation of soft segment in order to accelerate the more drastic movement of the polymer chain. The nonflammability of char layer was weakened as stoichiometric ratio of –OH to –NCO became larger, thus reducing flame-retardant and thermal stability. The limit oxygen index values of all materials exceeded 30%. The two-component varnish coatings had a pretty good water and solvent resistance.

Highly Efficient Photocatalytic Water Splitting over Edge-Modified Phosphorene Nanoribbons.

Two-dimensional phosphorene with desirable optoelectronic properties (ideal band gap, high carrier mobility, and strong visible light absorption) is a promising metal-free photocatalyst for water splitting. However, the band edge positions of the valence band maximum (VBM) and conduction band maximum (CBM) of phosphorene are higher than the redox potentials in photocatalytic water splitting reactions. Thus, phosphorene can only be used as the photocathode for hydrogen evolution reaction as a low-efficiency visible-light-driven photocatalyst for hydrogen production in solar water splitting cells. Here, we propose a new mechanism to improve the photocatalytic efficiency of phosphorene nanoribbons (PNRs) by modifying their edges for full reactions in photocatalytic water splitting. By employing first-principles density functional theory calculations, we find that pseudohalogen (CN and OCN) passivated PNRs not only show desired VBM and CBM band edge positions induced by edge electric dipole layer, but also possess intrinsic optoelectronic properties of phosphorene, for both water oxidation and hydrogen reduction in photocatalytic water splitting without using extra energy. Furthermore, our calculations also predict that the maximum energy conversion efficiency of heterojunction solar cells consisting of different edge-modified PNRs can be as high as 20% for photocatalytic water splitting.

High‐Efficiency Low‐Temperature ZnO Based Perovskite Solar Cells Based on Highly Polar, Nonwetting Self‐Assembled Molecular Layers

AbstractHerein, this study reports high‐efficiency, low‐temperature ZnO based planar perovskite solar cells (PSCs) with state‐of‐the‐art performance. They are achieved via a strategy that combines dual‐functional self‐assembled monolayer (SAM) modification of ZnO electron accepting layers (EALs) with sequential deposition of perovskite active layers. The SAMs, constructed from newly synthesized molecules with high dipole moments, act both as excellent surface wetting control layers and as electric dipole layers for ZnO‐EALs. The insertion of SAMs improves the quality of PbI2 layers and final perovskite layers during sequential deposition, while charge extraction is enhanced via electric dipole effects. Leveraged by SAM modification, our low‐temperature ZnO based PSCs achieve an unprecedentedly high power conversion efficiency of 18.82% with a VOC of 1.13 V, a JSC of 21.72 mA cm−2, and a FF of 0.76. The strategy used in this study can be further developed to produce additional performance enhancements or fabrication temperature reductions.

Composite process and electrothermal properties of a new-type electric heating plywood made with melamine resin adhesive film

A new type of electric heating plywood used for indoor heating products was made using melamine resin adhesive film (MRAF) as the bonding material and carbon fiber paper (CFP) as the electric heating material. Hot-press pressure greatly affected the permeation of the adhesive into the CFP and bonding performance, resulting in a bonding strength above 1.8 MPa. The conducting path in the electric heating layer was the main factor affecting the drop rate of resistance (DRR). Pressure of around 1.3 MPa was beneficial in controlling power deviation. Use of the MRAF improved insulation and water resistance. The plywood exhibited a surface temperature difference of 6 °C under commonly used power. Temperature rise exhibited an exponential relationship with heating time, and surface equilibrium temperature had a linear relationship with power density. The plywood had good power stability because the maximum resistance changed by only 0.44% when electricity was overloaded for 24 h at a power density of 500 W/m2. Stable resistance was presented after power was cycled 40 times, and the maximum DRR was 1.25% after 120 power cycles. This scheme offers a simple process for large-scale manufacture of the adopted MRAF, which has good bonding performance and electric heating stability.