Dissolution of Palladium Deposited onto a Fibrous Carbon Cathode in Nitric Acid Solution through Operation of a Short-Circuited Electrochemical System

Dissolution in 3.5 M NHO₃ of palladium deposited onto a fibrous carbon electrode from hydrochloric and nitric acid solutions was studied. The factors influencing the dissolution of palladium in contact with the electrode were revealed using a model of short-circuited electrochemical system.     

Electrolysis with Fibrous Carbon Electrodes in Recovery of Platinum Metals from Mineral and Secondary Raw Materials

Russian Journal of Applied Chemistry - Electrolytic recovery of platinum metals onto electrodes of fibrous carbon materials from solutions formed by processing of copper–nickel ores, gold-...     

On certain regularities of the response of a medium upon generation of the triple frequency of a few-period laser pulse in the case of its passage through an optically thin nonlinear layer

The response of a medium at the triple frequency under the action of few-period laser pulses is considered within the framework of the thin-optical-layer approximation for the case where the triple frequency is close to the natural frequency of the linear oscillator. It is shown that a bistable dependence of the polarization amplitudes on the external action amplitude simultaneously appears at both the natural frequency and the frequency of the external action. This allows one, in particular, to reveal the presence of bistability of the regime of third harmonic generation in a physical experiment by using the transmitted radiation of the acting pulse. A decrease in the duration of the pulse incident on the medium leads to an increase in the hysteresis loops. The effect of the absolute phase of a short pulse on the spectral composition of the response of the medium is studied. For pulses of medium duration, in addition to the resonant response of the medium, the presence of the dynamic response of the medium at the triple frequency was revealed, despite a detuning of the latter from the resonance. The presence of this frequency in the spectrum of the response of the medium results in the dependence of the resonant response of the medium on the absolute phase even for a sufficiently long pulse containing tens oscillations of the electric field strength under the pulse envelope. To obtain the dynamics of the spectral lines from the results of computer simulation, the Fourier-Gabor method is used, the applicability of which is demonstrated by the comparison of the results obtained on its basis with the corresponding analytical dependences.     

The effect of a strong light field on the spectrum shift of a hydrogen-like atom

Calculation results are presented for the transformation of the spectra of a hydrogen-like atom in an external nonhomogeneous field in the axisymmetric case and in plane geometry. Numerical results reported for prototype problems demonstrate the efficiency of the proposed algorithms. This research was partially support by grant No. 5142 of the program “Russian Universities: Basic Research.” Translated from Chislennye Metody v Matematicheskoi Fizike, Moscow State University, pp. 76–84, 1998.     

Effect of Anodic Polarization of Fibrous Carbon Electrode in Alkaline and Acid Solutions on the Distribution of Electrical Conductivity across the Electrode Thickness

The effect exerted by anodic treatment of electrodes with varied thickness, made of NT-1 low-conductivity carbonized material, in 0.07 M KOH and 0.25 M H₂SO₄ solutions on the distribution of the electrical conductivity across the electrode thickness at various anodic polarization conditions was studied.     

Dynamics of copper electrodeposition onto fibrous carbon electrodes

Distribution of copper electrodeposited from a sulfuric acid solution onto fibrous carbon electrodes, copper deposition rate, and current efficiency by the metal were studied in relation to the electrolysis duration, electrical conductivity of the electrode, geometric current density, and solution flow rate. The variation of the electrode thickness on which copper ions discharge at the limiting diffusion current at various solution flow rates and the electrode thickness on which the whole amount of oxygen dissolved in the electrolyte is reduced were calculated in relation to the solution flow rate and geometric current density. The main factors governing the distribution of copper across the electrode thickness and the electrolysis parameters from the beginning of the process till ??clogging?? of a part of the electrode by the metal were determined.     

Electrochemical modification of a nonwoven fibrous carbon material in sulfuric acid solution

The influence exerted by the electrode polarization of ANM nonwoven fibrous carbon material in 0.25 M sulfuric acid solution on the pore composition and size, fiber surface morphology, elemental composition of fibers, quantitative and qualitative composition of surface groups, stationary electrode potential, and electrochemical capacity was examined. These properties depend on the ratio of the cathodic and anodic constituents of the current density (measured per geometric surface area).     

Modifying Electrode Properties of Carbon-Fiber Materials by Electrolysis in Aqueous Solutions

The possibility of applying electrolysis in aqueous solution for the modification of electrode properties of carbon-fiber materials (CFM) is examined. It is shown that the cathodic and anodic polarization of CFM in solutions of acids and alkalis alters the state of the surface of fibers that constitute CFM, which is manifested in a change of the CFM electrode potential. The possibility of changing the CFM electroconductivity by an electrode treatment is demonstrated. This makes it possible to design electrodes with electroconductivity that varies over the electrode's thickness. The latter is of importance for both developing non-isoelectroconducting three-dimensional electrodes with a rigid matrix and comprehending operation principles of carbon-fiber electrodes. The obtained experimental data conform to the calculated dependences, specifically, profiles of electroconductivity and polarization over the electrode thickness are similar.     

Stability of Fibrous Carbon Materials in Cathodic Polarization in Nitric Acid Solutions

Stability and electrical conductivity of graphitized and carbonized fibrous carbon materials are studied in cathodic polarization in nitric acid solutions.     

Electrochemical oxidative modification of nanocarbon materials in aqueous electrolyte solutions

The effect exerted by electrochemical oxidative modification of carbon nanofibers and nanotubes by anodic and successive cathodic and anodic polarization in aqueous solutions of electrolytes H₂SO₄, CH₃COONH₄, HNO₃, (NH₄)₂SO₄, [H₂SO₄ + (NH₄)₂SO₄] on the structure and morphology of the fibers constituting the nanomaterials, on the composition of surface groups, on the stationary electrode potential of carbon nanofibers, and on properties of epoxy–carbon composites was studied. The results of the electrochemical modification were compared to the results of chemical modification of carbon nanofibers in a 6.0 M HNO₃ solution and of carbon nanotubes in a mixture of concentrated acids H₂SO₄ + HNO₃.