Regularities of solid phase crystallization on liquid metal electrodes

The measurement technique for the parameters of solid phase nucleation on liquid metal cathodes under electrolysis of molten salts is described. Their values are systematized and generalized for a wide range of temperatures, current densities, various deposited metals, liquid metal cathodes, emerging solid phases.     

Oxygen reduction at the interface of nonstoichiometric fluoride single crystals with metal electrodes

Electrochemical measurements are carried out on three-phase boundaries LaF₃:Eu²⁺/Me, oxygen gas, where Me = Ti, Be, Ta, Au and also on the boundaries of CeF₃:Sr²⁺ with Ag-supported Ag and Bi microelectrodes by the methods of linear scan voltammetry, chronoamperometry, and cyclic voltammetry. The conditions beneficial for reduction of oxygen gas, transformations of chemisorbed oxygen, and the appearance of its mobile forms are considered. Results on the interaction of gaseous oxygen with metals in contact with LaF₃:Eu²⁺ single crystals are generalized. The correlation is found between the oxygen reduction potential and the difference of electronegativities Δχ Me-O. The relationship is revealed between the oxygen reduction potential and the Me-Me bond energy by taking into account the structural factor f/k _n, where f is the number of binding electrons and k _n is the coordination number.     

Catalytic phenomena during the methanol oxidation at platinum electrodes in contact with solid polymer electrolytes

The methanol electrooxidation at platinum-gauze electrodes contacting a solid polymer electrolyte is studied in water and sulfuric-acid solutions by voltammetry in a broad potential range and by measuring steady-state currents and electrode coverages with chemisorbed species at low anodic potentials. The specific rate of the methanol oxidation in these systems is higher than that of similar platinum electrodes in liquid electrolytes. The catalytic action depends on the measurements conditions and the electrode potential. Reasons for catalytic effects at different potentials are discussed.     

Kinetics of CO2 nanobubble formation at the solid/water interface

The kinetics of adsorption of CO(2) molecules dissolved in aqueous solution onto a hydrophobised silica surface were investigated using a quartz crystal microbalance (QCM). The results of this investigation were compared with those obtained earlier from tapping mode atomic force microscopy (TMAFM) under the same experimental conditions (J. Yang, J. Duan, D. Fornasiero, J. Ralston, J. Phys. Chem. B., 2003, 107(25), 6139-6147; ref. 1). The QCM results represent the early stage of CO(2) gas adsorption (<20 min), before CO(2) gas bubbles adsorbed on the surface can be directly observed by TMAFM. The QCM results confirmed our observation from TMAFM imaging: that CO(2) gas molecules present in solution only adsorb on silica when its surface is hydrophobic. More importantly, the results showed that gas adsorption/bubble growth undergoes two consecutive kinetic processes: a slow and a fast adsorption process.     

Thin solid state reference electrodes for use in solid polymer electrolytes

This paper reports two low-profile (~ 10 μm thick) solid state reference electrodes for use in solid polymer electrolytes. The thin, open geometry of the electrodes enables close positioning between the working and counter electrodes. The first electrode uses the palladium hydride (Pd|PdH_x) couple (PHRE), and the second utilises the hydrous iridium oxide (IrO_x·yH₂O|IrO_a·bH₂O) couple (IORE). To our knowledge this is the first use of the latter as a reference electrode. The PHRE had a stable potential of + 70 mV vs RHE with a 4 mV h^− 1 drift and two hour lifetime, whilst the IORE gave a potential of + 847 mV vs RHE with a drift of 0.3 mV h^− 1 and no deterioration after 24 h of use. The use of these reference electrodes in a three-electrode solid state cell and a fuel cell is demonstrated.     

Modification of solid electrolyte interphase on deposited lithium metal by large separation between the electrodes in ether-based electrolytes

Journal of Solid State Electrochemistry - A thorough understanding of the lithium deposition behavior will facilitate the commercialization of lithium metal anodes. Despite enormous effort, an...     

Volta potential at metal-solid salt interface and real potentials of ions in solid electrolytes

Experimental conditions and results of investigations of Volta potentials of metal-solidelectrolyte and solid electrolyte-aqueous electrolyte solution by means of the dynamic condenser method are presented. These investigations were made for silver-silver halides and silver-silver nitrate as well as for cadmium-cadmium halide systems. On the basis of measured Volta potentials the real potentials of ions in these solid electrolytes are calculated. These real potentials are the ionic components of the crystalline lattice energy in the sense of the Gibbs energy.     

Kinetics of the phase separation of a low-viscosity liquid supersaturated with gas at the intermediate and later stages

The separation kinetics of a low-viscosity liquid supersaturated with gas is studied. It is shown that the number of bubbles per unit volume at the intermediate stage of the process remains virtually constant, whereas the amount of the gas per unit volume of the solution significantly decreases, almost attaining the equilibrium value. At the later stage, small subcritical bubbles disappear due to gas transfer to large supercritical bubbles; as a result, the number of bubbles in the virtually equilibrium (as to the dissolved gas) liquid decreases. For all the stages, the kinetics of the changes in the bubble distribution function and in the amount of gas per unit volume of the solution is determined.Translated from Kolloidnyi Zhurnal, Vol. 67, No. 1, 2005, pp. 94–105.Original Russian Text Copyright © 2005 by Slezov, Abyzov, Slezova.     

Methanol electrooxidation on platinum mesh electrodes bonded to solid polymer electrolytes

Methanol electrooxidation on smooth platinum electrodes bonded to solid polymer electrolytes was studied in water and acid solution by voltammetric measurements with different scanning rates. An enhancement of the oxidation rates was observed in these systems as compared to identical platinum electrodes in contact with liquid electrolytes. This electrocatalytic effect strongly depends on the measuring conditions and on the electrode potential. The reasons for the catalytic effects at different potentials are discussed. Received: 8 January 1997 / Accepted: 1 December 1997     

Constructing nitrided interfaces for stabilizing Li metal electrodes in liquid electrolytes

Traditional Li ion batteries based on intercalation-type anodes have been approaching their theoretical limitations in energy density. Replacing the traditional anode with metallic Li has been regarded as the ultimate strategy to develop next-generation high-energy-density Li batteries. Unfortunately, the practical application of Li metal batteries has been hindered by Li dendrite growth, unstable Li/electrolyte interfaces, and Li pulverization during battery cycling. Interfacial modification can effectively solve these challenges and nitrided interfaces stand out among other functional layers because of their impressive effects on regulating Li⁺ flux distribution, facilitating Li⁺ diffusion through the solid-electrolyte interphase, and passivating the active surface of Li metal electrodes. Although various designs for nitrided interfaces have been put forward in the last few years, there is no paper that specialized in reviewing these advances and discussing prospects. In consideration of this, we make a systematic summary and give our comments based on our understanding. In addition, a comprehensive perspective on the future development of nitrided interfaces and rational Li/electrolyte interface design for Li metal electrodes is included.

In this perspective, we make a systematic summary and give out our comments on constructing nitrided interfaces for stabilizing Li metal electrodes.     

Heavy water reactions with alkaline-earth metal dications in the gas phase: Kinetics at room temperature

Room temperature rate coefficients and product distributions are reported for the reactions initiated in D₂O with dications of the alkaline-earth metals Mg, Ca, Sr and Ba. The measurements were performed with a selected-ion flow tube (SIFT) tandem mass spectrometer and electrospray ionization (ESI). Mg²⁺ reacts with water by a fast electron transfer leading to charge separation with a rate coefficient of 1.4 × 10⁻⁹ cm³ molecule⁻¹ s⁻¹. Ca²⁺ reacts with D₂O in a first step to form the adduct Ca²⁺(D₂O), with an effective bimolecular rate coefficient of 2.3 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, which then undergoes rapid charge separation by deuteron transfer to form CaOD⁺ and D₃O⁺ in a second step with k = 7.9 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹. The CaOD⁺ ion reacts further by clustering up to five more D₂O molecules. Sr²⁺ clusters up to eight D₂O molecules and Ba²⁺ up to seven D₂O molecules, with the first addition of D₂O being rate determining in each case and the last addition being distinctly slower, as might be expected from a transition in the occupation of the added water molecules from an inner to an outer hydration shell.     

Kinetics of Lisinopril degradation in solid phase

Summary The kinetics of degradation of lisinopril (LIS) in solid phase in presence of humidity at 343, 353, 358 and 363 K has been investigated. Changes of the LIS concentration were followed by an HPLC method with UV detection. The thermodynamic parameters at 293 K of degradation of LIS in solid phase E_a (kJ/mol) = 166 ± 47; H*(kJ/mol) = 163 ± 48; S*(J/(K × mol)) = 99 ± 135 for RH = 76.4% have been calculated. Identification of the product of LIS degradation in solid phase was carried out by HPLC-MS. Diketopiperazine derivative of LIS was the major product of its decomposition in the presence of humidity.     

Mechanisms of photoluminescence at cds polycrystalline electrodes in contact with aqueous electrolytes

The red and infrared emissions in the photoluminescence spectra of polycrystalline CdS electrodes have been studied as a function of the atmosphere and temperature of annealing, excitation light intensity, applied bias and electrolyte composition. The experimental results suggest that the red luminescence is associated with a recombination mechanism involving valence band holes and electrons trapped at sulfur vacancies at about 0.7 eV below the conduction band edge. Infrared emission seems to involve, besides sulfur vacancies, cadmium vacancies (hole traps) at about 0.3 eV above the valence band edge. Both hole injection rate and concentration of S and Cd vacancies are the parameters determining the shape of the luminescence spectra.     

Static electrification of solid oxide in liquid metal and electrical double layer at the interface

Static electrification of a solid oxide, say a semiconducting oxide in liquid metal, is mainly due to electron transfer between two phases. Excess electrons in the liquid metal phase provided by the oxide give rise to an electrical double layer at the interface. The electrical double layer may be divided into three parts, an immobile inner layer, a compressed diffuse layer, and a flat layer extending into the bulk liquid metal. Differential potential analysis and the induced emf method were used to measure the potential of the compressed diffuse layer and the excess electron density of the flat layer, respectively. Results show that most oxides in liquid metals carry positive charges on their surfaces and the potentials of the compressed diffuse layer are in the range of 3 to 42 microV. Such a low potential implies that the diffuse layer is considerably compressed. The excess electron densities of the flat layer are on the order of 10(22) electrons/m(3) of Hg and their contributions to surface charges of oxide are in the range of 10(17) to 10(18) charges/m(2) for the oxide/mercury systems with a solid density of 0.3 wt% at room temperature.     

Revealing the solid electrolyte interface on calcium metal anodes

Owing to its low potential, crustal abundances and environmental friendliness, calcium metal anode(CMA) is emerging as a powerful contender in post-lithium era. However, the passivation of CMA fatally hinders its development. Recently, several feasible electrolytes have been developed. Nevertheless, as a pivotal part, the solid electrolyte interface(SEI) formed on CMA has not been paid enough attention to. In this review, based on the passivation mechanism of CMA, the favorable composition of SE...     

Thin surfactant layers at the solid interface

The formation of surfactant layers on solid surfaces is an important process in many industrial applications. The structure of these layers influences the properties of the solid in processing and use. We summarize the literature data on the structure of surfactant layers at the solid/liquid interface and our own results characterizing the interactions between solid surfaces and solutions or emulsions. Ideas are presented for the processes taking place at the solid surface during drying by heat treatment. An outlook is given of how to investigate surfactant layers on dry surfaces. Received: 11 July 1999/Accepted: 2 May 2000     

Anodic behavior of ephedrine at solid electrodes

The electrooxidation of the alkaloid ephedrine at solid electrodes in a wide range of concentrations and pH values of solutions has been studied by the methods of potentiodynamic voltammetric curves, preparative electrolysis, and quantum-chemical calculations by the SCF MO LCAO method in the MINDO/3 approximation. A quantitative basis has been given for the sequence of stages in the electrooxidation of ephedrine proposed previously by the authors of one of the cited papers. Good agreement has been established between the values found theoretically and experimentally. Institute of Organic Synthesis and Colloid Chemistry, Kazakh SSR Academy of Sciences, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 523–526, July–August, 1989.     

Electrochemical study of carminomycin at solid electrodes

The electrochemical behaviour of carminomycin at carbon-paste, glassy-carbon and composite carbon—polymer electrodes has been compared. Three electroactive sites on the molecule have been identified. Two sites are involved in the oxidation processes, the first corresponding to the hydroquinone structure in the C-6/C-11 positions, the second attributed to the C-4 phenolic function. Applying a negative-going scan allows reduction of the quinone moiety in the C-5/C-12 positions. Both the quinone and hydroquinone functions exhibit quasi-reversible electrochemical reactions in acidic medium, becoming irreversible in alkaline solution. Adsorption phenomena accompany both the oxidation and reduction processes, primarily in neutral and alkaline media. The adsorption can be decreased by using the composite electrode, which is less sensitive to surface phenomena. This working electrode is proposed as the most suitable for the determination of carminomycin at pH 1. A linear calibration plot can be obtained over the range 1 × 10⁻⁶-1 × 10⁻⁴M, with a limit of detection of 6 × 10⁻⁸M.