V. I. Vigdorovich

Kinetics of hydrogen evolution in acidic environments on pressed micrographite electrodes modified with carbon nanotubes. I. Polarization studies

The kinetics of cathodic hydrogen evolution on pressed micrographite electrodes containing up to 8 wt % multiwalled carbon nanotubes is studied. The effects of the potential scan rate, concentration of nanotubes, direction (forward or reverse) of polarization, acidity of environment, and electrode potential are discovered.

Inhibition of corrosion and hydrogenation of carbon steel in media containing hydrogen sulfide and carbon dioxide with low concentrations of salts of oxyethylated amines

Impedance spectroscopy was used to study the protective action of salts of higher aliphatic oxyethylated amines as universal inhibitors of the hydrogen sulfide and carbon dioxide corrosion and hydrogenation of carbon steel.

A Study of Hydrogen Accumulation in Multiwall Carbon Nanotubes by Electrochemical Techniques

Accumulation of electrolytic hydrogen in alkaline medium (5 M KOH) by multiwall carbon nanotubes (MWCNTs) 20–60 nm in inner diameter and 2 μm in length obtained by catalytic pyrolysis of propane/butane mixture has been studied by means of the electrochemical diffusion technique, cyclic voltammetry, and impedance spectroscopy. MWCNTs were applied on a steel membrane and were encapsulated by a 10-nm electrolytic nickel layer. Cyclic voltammograms were recorded in the range of potentials from −1.2 to +0.2 V and contained a current peak in the cathode region corresponding to hydrogen absorption by nanotubes at −0.9 V and current peak in the anode region corresponding to oxidation of absorbed hydrogen at −0.6 V. Hydrogen storage capacity of MWCNTs varies from 4.6 to 6.5% depending on the amount of nanotubes according to electrochemical diffusion data. The electrochemical impedance data correlate with the results of the above methods.

Surface state of carbon materials and accumulation of hydrogen in multiwalled carbon nanotubes

Literature data on the nature of oxide structures formed on the surface and in the bulk of carbon materials, including carbon black, multiwalled nanotubes (MWNTs), and carbon fiber are generalized. Positive and negative effects of oxide structures on the properties of MWNTs and the possibilities of their practical utilization are considered. The probable nature of the surface and bulk oxide structures is discussed. The effect of the cathodic polarization value and the nature and composition of the electrolyte on the accumulation of hydrogen in MWNTs directly applied on a steel membrane or involved in an Epoxy-resin-based composite is studied. In an acidic environment (x M HCl + (1 − x) M LiCl), the amount of hydrogen accumulated by carbon nanotubes in a Fe/MWNT system is shown to vary in a range of 3–13.8 wt % and increase with an increase in the acidity of the environment at the cathodic shift of the potential by 0.2 V from the steady-state value (in the absence of external field). In an alkaline environment (1 M KOH), the amount of absorbed hydrogen is 3.5–15 wt % depending on the cathodic polarization (up to 0.4 V) and the weight of multiwalled nanotubes.

Suppression of nanoscale effects in nanomaterials by gas- and liquid-phase adsorbates

The possibility and methods of suppressing the activity of adsorption sites of nanomaterials by an example of iron and zinc with water molecules and oxygen, including the conditions of low relative humidity and air pressure of 10−5 Pa, are considered.

Kinetics of hydrogen evolution from acidic solutions on pressed micro graphite electrodes modified with carbon nanotubes. II. Impedance studies

The kinetics of hydrogen evolution on pressed micro graphite electrodes modified with multi-walled carbon nanotubes (MWCNTs) is studied in chloride environments with a constant ionic strength equal to unity with the use of impedance spectroscopy. The impedance of electrodes containing from 0.1 to 8 wt % MWCNTs in solutions of a general composition x M HCl + (1 − x) M NaCl at a currentless potential and at E = −0.6 V (N.H.S.) is interpreted as impedance of porous electrodes. The data obtained indicate the absence of diffusion limitations of the processes that proceed at a currentless potential and of the hydrogen evolution reaction. When the content of MWCNTs in a micro graphite electrode increases to 8 wt % at E = −0.6 V (N.H.S.), the increase in the contribution of the double layer capacitance and the adsorption capacitance to the Faraday impedance is the most pronounced, which means that MWCNTs promote a specific interaction of the electrolyte ions and atomic hydrogen with the surface of the cathodically polarized electrode.

The Effect of Nanocomposite Superhydrophobic Coating on Corrosion and Kinetics of Electrode Processes on Steel in 0.5 M NaCl Solution

The corrosion and kinetics of partial electrode reactions on St3 carbon steel with a superhydrophobic coating based on methoxy fluorobutylsilane derivatives in 0.5 M NaCl solution were studied. This influence of in situ duration τ of the medium’s corrosive action (0.5–144 h) on its protective effect is considered. This allows reduction of overall corrosion rate by 23 ± 3 times, when the stationary state is reached. The kinetics of cathodic reduction of dissolved oxygen and steel anodic ionization is also considered. In the initial stages of corrosive action of neutral aerated chloride medium (until steady-state characteristics are reached), steel at potential E near Ecor corrodes in the active state, whereas, when τ is ≤0.5 h, it corrodes under anodic control conditions, and then the control is replaced with a cathodic one.

Kinetics and mechanism of electrode reactions in corrosion of some metals covered with oil films in acid and neutral chloride environments

Kinetics of electrode reduction reactions of dissolved molecular oxygen and hydrogen ions upon corrosion of copper and carbon steel was studied in neutral (NaCl) and weakly acidic (HCl) media. It was shown that deposition of the films comprised of trade or waste petroleum and synthetic (poly-α-olefins) oils on the studied metals does not alter the kinetic parameters of the electrode processes both in the kinetic region and in controlling mass transfer conditions. The observed regularities were explained as being results of the high porosity of the used oil films regardless of their kind.

Dependence of binding energy of atoms in low-nuclear clusters on number of particles forming them. Cu n , Ag n , and Au n clusters

On the basis of generalized literary data, the binding energy and chemical activity of components of low-nuclear Cun, Agn, and Aun clusters has been determined as a function of the value of n (n = 2–8). By means of the graphic analysis, the values of n of clusters of the studied metals at which the binding energy is identical to this value in a maternal phase (n = 19–21) has been determined.

Some features of hydrogen evolution reaction on iron with surfactant on the example of o-fluorophenylbiguanidine

It has been shown that, when there is o-fluorophenylbiguanidine (o-FPBG) and its concentration increases (from 0.5 to 40 mM), the change of the nature of slow step of hydrogen evolution on iron is observed in the following order: slow discharge → limiting chemical recombination → slow lateral diffusion → limiting discharge. This series is in sufficient correlation with the experimental adsorption isotherm of o-FPBG on iron.