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Effects of adding varied amounts of copper to carbon-supported nickel particles on their structure, composition and electrocatalytic activity for the hydrogen oxidation and evolution reactions in alkaline medium have been explored. Ni1-x Cu x /C catalysts were prepared by the incipient wetness impregnation. Comprehensive characterization of the catalysts included X-ray powder diffraction, X-ray photoelectron spectroscopic, transmission electron microscopic and cyclic voltammetric analyses, while atomistic Monte Carlo simulations have been undertaken to obtain further insights into the structure of the bimetallic NiCu nanoparticles. We found that compared to monometallic Ni, NiCu nanoparticles show lower propensity towards oxidation under ambient conditions. Furthermore, we report that adding Cu allows increasing the surface-weighted electrocatalytic activity, and the specific surface area of Ni1-x Cu x /C electrodes, both contributing to a ca four-fold enhancement of the mass-weighted activity. The nature of the synergistic interactions between Ni and Cu is proposed on the basis of the analysis of experimental data and Monte Carlo structural modelling results.

Solvent dynamics effects on the electroreduction of [PtCl3(H2O)]− at a mercury electrode are explored in the framework of Sumi–Marcus model using an efficient computational scheme. According to results of density functional calculations, the second electron transfer step may be regarded as rate controlling. The nonmonotonous influence of solvent viscosity on the reaction rate is predicted and explained in terms of the saddle point avoidance. The results of model calculations are employed to interpret experimental data reported earlier in the literature.

The advantages of corrected Marcus plots as compared to the more traditional corrected Tafel plots are discussed and illustrated by the treatment of experimental data. The procedures are proposed to avoid the uncertainties of EDL correction and to estimate the reliable values of transmission coefficient and total reorganization energy. Special emphasis is placed on the diagnostics of activationless reactions in frames of the same method.

The fluoride ion adsorption from a gas phase on various faces of a single crystal of silver is studied by a density functional method within a cluster model for metal. The adsorption bond energy is found to increase in the series Ag(100) < Ag(111) < Ag(311) < Ag(110). A substantial structural and energetic heterogeneity of various adsorption sites is revealed. The results are utilized to simulate the electrochemical interface between individual faces of a single crystal of silver and aqueous solutions containing the fluoride ion. It is assumed that the adsorption potential may be represented as the sum of two contributions, one of which describes the metal–ion interaction and the other, the ion solvation energy. The plotted adsorption terms take into account partial degradation of the fluoride ion when adsorbed from an aqueous solution. Estimates of discreteness of the electrical double layer are presented. A conclusion on the maximum manifestation of specific adsorption of the fluoride ion for the Ag(100) face is made.

The adsorption of the chloride ion and chlorine atom on clusters simulating the surface of the (111) and (001) faces of the crystal lattice of indium and liquid gallium are calculated using the Hartree–Fock–Roothaan and density functional (B3LYP) quantum-chemical methods. The energy of adsorption of chloride ions from a gas phase at these faces increases in the following series: bridge≈hollow < on-top positions and equals to ∼179 kJ mol–1 for In(111) and ∼183 kJ mol–1 for gallium in the on-top position. Both metals exhibit similarity in the formation of bonds between their surface atoms and the adsorbate. The adsorbate charge does not depend on the adsorbed form (chloride ion or chlorine atom) and equals ∼ 0.5e. Parameter of a virial adsorption isotherm is estimated with allowance for coulombic interactions near the metal/electrolyte interface.

Approaches to perfecting analysis of psi-prime effects, based on modeling the reaction layer of electrochemical reactions and allowing for real molecular structure of reactants and products, are considered. Conditions of applicability of the traditional slow-discharge theory relations to systems with reactants of complicated structure are analyzed in a wide overvoltage interval. Special attention is paid to the problem of accounting for nonuniformity of charge distributions in particles of reactants and products. It is shown that it becomes essential to account for the dielectricity of the effective cavity used for modeling the particles, provided the particles are sufficiently large.

Quantum-chemical approaches that have been used lately for computing Franck–Condon barriers for electron transfer reactions are analyzed. Attention is focused on the processes whose description goes beyond the linear response approximation, including redox reactions with the cleavage of chemical bonds. Various approaches that take into account the solvation effects are discussed. The role played by the cluster models of the electrode in the description of specific interaction of reactants and products with the electrode surface is emphasized. The influence the dynamics of the nearest coordination sphere of metal aquacomplexes has on the electron transfer rate are interpreted anew. Examples of calculation of the electron penetration probability are considered, and important qualitative effects associated with the dependence of this parameter on the reactant orientation and the electrode charge are analyzed. Urgent problems the quantum electrochemistry faces in the near future are reviewed.

The polarization curves for the S2O82- electroreduction on a mercury electrode at high overvoltages and various concentrations of a surface-inactive supporting electrolyte are modeled within modern theory of charge transfer in polar media and quantum-chemical approaches. Based on an analysis of the reactant adsorption in terms of a cluster model, the conclusion is drawn that the persulfate ion is localized in the diffuse part of EDL. When calculated the current, it was assumed that the transfer of the first electron, accompanied by the bond cleavage, is the limiting stage of the total two-electron process. The integration if performed over the entire electron spectrum of the metallic electrode and an attempt is made to account for electrostatic and solvation effects on a molecular level. It is shown that the experimentally-studied overvoltage interval corresponds to the occurrence of the process near the activationless region. The increase in the current at high negative charges of the surface is due to an increase in the reaction layer thickness. This effect arises from a change in the ratio between contributions made by the reactants at the distance of closest approach and the species farther away.

The effect of the ligand surrounding on the character and degree of the inner-sphere reorganization during electroreduction of aqua, aquahydroxy, hydroxy, and Edta complexes of zinc(II) is studied in the framework of a quantum-chemical approach. It is established that the most substantial intramolecular reorganization occurs during the transfer of the first electron onto [Zn(Edta)]2–. The solvent's reorganization energy is estimated.

Experimental cathodic polarization curves, obtained on a mercury electrode in 0.33 mM K3[Fe(CN)6] + 0–1.5 mM KCl solutions, are analyzed quantitatively. On the basis of quantum-chemical calculations of the geometry of species [Fe(CN)6]3– and [Fe(CN)6]4– and charge distributions in them, it is shown that the species interaction with the EDL field is equivalent to a repulsive interaction between effective point charges localized near anion centers in the diffuse layer. The effective Born radius of ferricyanide anion and the solvent reorganization energy are calculated, and inner-sphere constituents of the energy are estimated. These parameters are used for computing theoretical dependences of the transfer coefficient α on the overvoltage via the equation of the quantum-mechanical theory of elementary act. The value of α, determined from corrected Tafel plots, is shown to substantially depend on the assumptions adopted when analyzing the system in the framework of the classical slow-discharge theory; it is close to the theoretical value only if the participation of anion–cation associates formed in the bulk solution is taken into account. Such an approach explains the weak temperature dependence of the process rate. The experimental facts do not contradict theoretical prediction that the reaction occurs in the vicinity of the activationless region.