Sergey Yu. Vassiliev

Quasitemplate synthesis of nanostructured palladium electroplates

Abstract By means of quasitemplate electrodeposition of palladium from palladium chloride solutions with additions of polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP), palladium deposits with high specific surface areas (up to 50 m 2 g −1 ) are synthesized. The specific surface areas of the deposits tend to increase with an increase in the chain length of a polymeric additive. Some of the deposits synthesized exhibit a high hydrogen sorption capacity and in this respect resemble the highly defective palladium deposits formed at hydride formation potentials in the absence of polymer additives. According to SEM and STM data, the details of globular micrometer-scale structure of the deposits depend on the polymer nature. PEG addition results in the oriented growth of the rows of nanoparticles, whereas PVP does not affect the mutual orientation of the latter. The minimal diameter of the imaged separated particles in the globulas equals 5 nm for PEGPd and at least 15 nm for PVPPd. Comparison with electrochemically determined true surface areas demonstrates rare coalescence of nanoparticles. Electrodes formed in PVP-containing solutions are found to exhibit enhanced electrocatalytic activity towards NO 3 − electroreduction at the potentials close to the reversible hydrogen electrode.

Inhomogeneous films of conducting polymers—STM and electrochemical characterisation

Abstract The comparative CV and STM data for electrodeposited poly-metoxyaniline films (30–300 nm thickness) are presented before and after treatment by ethanol, under the assumption that the oligomeric fragments are preferentially dissolved under this treatment. The samples are fabricated in both sulphuric and perchloric acids, the latter resulting in higher fractions of oligomers. The measurements of voltage–height dependencies are used to test local features of fragments in inhomogeneous polymer films. An approach is proposed for the interpretation of conducting polymer images.

Lithium Ion Coupled Electron-Transfer Rates in Superconcentrated Electrolytes: Exploring the Bottlenecks for Fast Charge-Transfer Rates with LiMn2O4 Cathode Materials

The charge-transfer kinetics of lithium ion intercalation into LixMn2O4 cathode materials was examined in dilute and concentrated aqueous and carbonate LiTFSI solutions using electrochemical methods. Distinctive trends in ion intercalation rates were observed between water-based and ethylene carbonate/diethyl carbonate solutions. The influence of the solution concentration on the rate of lithium ion transfer in aqueous media can be tentatively attributed to the process associated with Mn dissolution, whereas in carbonate solutions the rate is influenced by the formation of a concentration-dependent solid electrolyte interface (SEI). Some indications of SEI layer formation at electrode surfaces in carbonate solutions after cycling are detected by X-ray photoelectron spectroscopy. The general consequences related to the application of superconcentrated electrolytes for use in advanced energy storage cathodes are outlined and discussed.

Microstructural Aspects of the Degradation Behavior of SnO2-Based Anodes for Aluminum Electrolysis

cZAO NTTs Bakor, Sherbinka, 142171 Moscow, Russia The performance of SnO2 ceramic anodes doped with copper and antimony oxides was examined in cryolite alumina melts under anodic polarization at different cryolite ratios, temperatures, times, and current densities. The corroded part consists of a narrow strong corrosion zone at the anode surface with damage of the intergrain contacts and a large increase in porosity, a wider moderate corrosion zone with a smaller porosity increase, and a Cu depletion zone, where the ceramic retains its initial microstructure and a slight porosity increase occurs due to the removal of the Cu-rich inclusions. Mechanical destruction of the anode was never observed in the 10–100 h tests. A microstructural model of the ceramic was suggested, consisting of grains with an Sb-doped SnO2 grain core surrounded by an 200 to 500 nm grain shell where SnO2 was simultaneously doped with Sb and M n+

Specific Molecular Features of Potassium-Containing Cryolite Melts

Experimental in situ Raman spectra are presented for potassium, sodium and mixed fluoroaluminate melts. More acidic melts with cryolite ratio (CR) below 2 are accented. The cation-dependent ratio of integral band intensities is assigned to specific interactions of potassium cations with low coordinated fluoroaluminates. For alumina containing melts, the effect of potassium on the stoichiometry of predominating oxofluoroaluminate anion is observed indirectly. Density functional theory is employed to investigate the behavior of different fluoroaluminates (including dimers) and their associates formed by alkali metal cations.