卷 52, 编号 5 (2016)

The effect of hydrophilic walls on the structure of the hydration shell of a Cl⁻ ion is studied in terms of the model flat nanopore in contact with water vapors at room temperature by the Monte Carlo computerassisted simulations. In the field of hydrophilic walls, the hydration shell falls into two parts: the ion-enveloping part and the molecular-film spots spread over the wall surface above and under the ion. Both parts have the pronounced radial-layered structure. The three-dimensional scheme of distribution of the averaged local shell density represents a system of conical coaxial layers expanding in the direction from wall to ion. The effect of forcing out the ion from its own hydration shell is also observed for hydrophilic walls. The specific electric polarizability of the shell is strongly anisotropic. Its longitudinal component is several times larger than the transversal component and behaves nonmonotonically as the hydration shell grows, passing through the maximum. The molecular order near the walls is characterized by the preferential orientation of the molecule plane in parallel to the wall plane and the turn of symmetry axes of molecules in the direction parallel to the normal to the pore plane in the vicinity of the ion.

Dimensionally stable anode (DSA) of antimony-doped tin dioxide electrode based on TiO₂-nanotube arrays (NTs) has been successfully fabricated through thermal decomposition. The surface morphology and composition of the electrodes were characterized by using scanning electron microscopy and X-ray diffraction. Methyl orange (MO) was used as a model pollutant to investigate the electrochemical properties of these two electrodes. The optimized anodic oxidation voltage and time for TiO₂-nanotubes array based DSA electrode is 60 V and 10 min, respectively. The results show that Ti/TiO₂–NTs/Sb–SnO2 electrode has an increase of 100 mV in oxygen evolution overpotential and the service life is 56% longer than that of the traditional DSA electrode. Under the optimum conditions, MO solution decolorization rate and TOC removal rate reached approximately 100 and 80%, respectively. Study suggested that the as-prepared Ti/TiO₂–NTs/Sb–SnO2 DSA electrode exhibits high activity for degradation of organic pollutant with high concentration.

La_1.8Ti_0.2MgNi_9–xCo_x (x = 0, 0.1, 0.3, 0.5) alloys were prepared by magnetic levitation melting under argon atmosphere. The effects of Co substitution on the phase structure and the hydrogen storage properties of the alloys were investigated. The results show that LaNi₅ and LaMg₂Ni₉ phases are contained in all experimental alloys. LaNi₃ phase disappears and LaNi₂ phase appears as x ≥ 0.1 and x ≥ 0.3, respectively. Electrochemical performances have been improved after Co substitution for Ni, for example, the discharge capacity and the high rate dischargeability (HRD) reach the maximum at x = 0.1, and the optimum cycling stability is obtained at x = 0.5. The positive impact of Co on the hydrogen diffusion rate in bulk enhances the HRD, but to high Co content (x ≥ 0.3), the unsatisfied hydrogen desorption capability brings relative low HRD compared with the alloy electrode at x = 0.1.

A device designed for research of heat phenomena occurring in chemical power sources (CPS) is described. The device includes two functional blocks: electrochemical and calorimetrical, operating under single control, which allows simultaneously performing electrochemical and calorimetric measurements. The calorimetric block is a heat flow calorimeter. The calorimetric chamber design provides the possibility of studying thermal processes in laboratory electrochemical cells and CPS of planar, disk, and prismatic design. The absolute measurement error of the heat flow is ±50 μW at the resolution of 1 μW. The operating temperature range of the calorimetric chamber is 0–90°C. The basis of the electrochemical block is a module of a four–range potentiostat–galvanostat. The maximum polarizing current of the potentiostat is ±200 mA at the maximum voltage on the auxiliary electrode of ±10 V. Multiuser remote access from the user computers over Ethernet to the device is provided for control and treatment of experimental data. Digital deconvolution filters allowing to compensate the response rate of the heat flow meter are used for processing primary data of calorimetric measurements.

The corrosion behavior of pure (99.999) aluminum in 1 M HCl solution is studied. The regularities of local gas evolution on the surface of test specimen at the open-circuit potential are determined. A number of sites, where hydrogen gas evolves, varies with the time passing through a maximum. The sizes of bubbles prior to their detachment from the specimen surface are determined. The time dependences of gas bubble radius in the course of the bubble growth are obtained. From the experimental results, it is concluded that, at the sites of hydrogen gas evolution, the cathodic reaction prevails, whereas the anodic reaction (aluminum etching) proceeds at the rest specimen surface area. No pits form at the sites of hydrogen evolution during the experiments (up to 5 h). The quantitative analysis of the cathodic polarization curve enabled us to estimate the rate (the corrosion current density) of almost general corrosion after the decay of local gas evolution. The long-term experiments (for 2 months) showed that the pitting corrosion of pure aluminum takes place in 1 M HCl.

For the first time, the electrochemical synthesis of gold nanostructures was done at the surface of carbon paste electrode. This device was used as a simple and sensitive electrochemical sensor for measurement of pyridoxine (Vitamin B₆, VB₆). The diffusion coefficient (D) and the kinetic parameters such as electron transfer coefficient (α) and catalytic rate constant (k) for VB₆ were also determined using electrochemical approaches. The cyclic voltammetry method showed VB₆ oxidation reaction with irreversible characteristics was diffusion-controlled at low scan rates. Using differential pulse voltammetry (DPV), the peak current was linearly dependent on VB₆ concentration in the ranges of 1.9–110.8 and 110.8–257.0 μM, with detection limit of 74.0 nM, respectively. Results showed there is no interference of other vitamins in oxidation of VB₆. DPV was used to quantify of VB₆ in some real samples by the standard addition method. The modified electrode showed good sensitivity and stability.

The method of impedancemetry is used to study electrochemical activity of platinum electrodes in contact with the solid electrolyte of YSZ (ZrO2+10 mol % Y₂O₃). Electrodes are activated by small additives of pradeodymium oxide PrO_x (0.1–0.3 mg/cm²) by their impregnation by praseodymium nitrate solution with the further thermal treatment at 850°C and are studied in the cases when PrO_x forms a film on the electrolyte and when no activator film is formed. The effect of the number of electrode activations on the electrochemical activity of platinum electrodes is studied.