•Density functional theory calculation of electrode potential-dependent Gibbs Energy•Equilibrating electrode potential-dependent Gibbs energies of reactants and products•Predicting electrode-potential changes in structures at electrochemical interfaces•Predicting pH dependencies of interfacial reversible potentials and structures•Predicting non-linear dependencies of interfacial reversible potentials on pHIt is shown how to adopt the Nernst equation to electrode potential-dependent Gibbs energies, calculated for reactants and products from density functional theory, to make predictions of reversible potentials for redox reactions on electrode surfaces in electrolytes of any pH. The theory is general because any spectator species may be included in electrochemical interface. We demonstrate its application to H and OH deposition on Pt(111).

It has been shown recently that when reactants and products are well modeled within a comprehensive self-consistent theory for the electrochemical interface, accurate predictions are possible for reversible potentials, Urev, in acid electrolyte for reactions such as reduction of H+(aq) to form under potential deposited H(ads) and oxidation of an OH bond of H2O(ads) to deposit OH(ads). Predictions are based on calculated Gibbs energies for the reactant and product being equal at the reversible potential, which is the potential at the crossing point for reaction and product Gibbs energies, plotted as functions of electrode potential. In this Letter, it is demonstrated that the same capability holds for these reactions in basic electrolyte. This demonstration opens up the opportunity for predictions of reversible potentials and mechanisms for other electrocatalytic reactions in base.

In this article, we present a mechanism for electroless copper deposition from alkaline solutions containing [CuIIEDTA]2–(aq) and hydrolyzed aldehydes. The mechanism is based on quantum chemical calculations of the activation energies and reversible electron-transfer potentials. Low-coordinated, electroless-deposited surface Cu atoms are found to activate H abstraction from the C–H bond of the aldehyde group, putting H on the surface and releasing a highly reducing electron in the process; this electron reduces [CuIIEDTA]2–(aq) to [CuIEDTA]3–(aq). [CuIEDTA]3–(aq) is subsequently reduced to Cu0(ads) by a second electron generated by the same process, releasing EDTA4–(aq). Calculated reversible potentials for the reduction steps aid in interpretation of the catalytic behavior observed in experimental polarization curves.

Results from a comprehensive approach to predicting and explaining activities of 13 transition metal cathode materials toward oxygen electroreduction are presented. Effective reversible potentials for four-electron reduction were calculated based on exergonic O–O bond scission for OOH and O2 on Pt(111), Pt monolayer skins on Pd(111), Pt3Cu(111), Ir(111), Pt3Ni(111), Pt3Co(111), Au(111), Rh(111), Pt3Fe(111), Ru(0001), Ag(111), Pt3Ti(111), and, finally, on pure Au(111). All values based on the OOH(ads) route were several hundred millivolts less than the 1.23 V standard value for the four-electron reduction. Although the route where O2 dissociates was calculated to have higher values for their effective reversible potentials, predicted activation energies were also high, precluding this possibility in most cases. Comparison of predicted effective reversible potentials, which spanned a range of 0.3 V and measured reduction onset potentials, which according to the literature span a narrower ∼0.1 V range, suggests the possibility that higher activation energies will for some materials reduce the measured onset potentials to values less than the effective reversible potentials. Assignments based on the energy scaling model to the left- or right-hand sides of volcano-shaped activity plots at 900 mV vs O and OH adsorption bond strengths were found to be correct when the former was used. It was found for all 13 materials that the Gibbs adsorption bond strengths of OOH are at least 0.9 eV less than the ideal value of 1.35 eV, and an important goal is to reduce this gap through the discovery of new catalysts. When this is accomplished, it will be possible to construct volcano plots using current densities measured at electrode potentials approaching 1.23 V.

The ionization potentials and the electron affinities of doped diamond were calculated using B3LYP hybrid density functional theory and nanocrystalline cluster models, while taking into account the quantum confinement of the charge carriers. In many cases donor and acceptor levels were created in the middle of the gap between the conduction and valence bands. A possible explanation for the n-type behavior created by co-doping diamond films with boron and sulfur is given in terms of thermally activated electron donation from an SVS (V is vacancy) donor to a BB acceptor band. Both lie deep in the band gap. It is proposed that electrons in the BB acceptor band are mobile charge carriers. It is also proposed that the conversion of boron-doped diamond from p-type conductivity, with hole charge carriers in the top of the valence band, to n-type conductivity, following treatment in a deuterium plasma, may arise from formation of interstitial hydrogen donor levels and BnHm acceptor levels that create an acceptor band in which electrons are mobile. Again, both are deep in the band gap of pure diamond. In a prior attempt to explain this n-type behavior, BHn defects with unrelaxed structures were proposed to be shallow donors to the diamond conduction band. This paper shows that these defects become deep donors when their structures are optimized. Finally, defects created from vacancies with 1 to 4 H in them are shown to be deep donors to the diamond conduction band.

•Presents brief historical background for theory in electrochemistry.•Outlines quantum chemical calculation approaches for electrochemical interface.•Discusses applications of theories to activation energies and reversible potentials.•Shows how electrode potential is introduced in the most current theory.•Suggests theory will have an increasingly important impact on electrochemistry.In the nearly 100 years since Faraday published his paper “On Electrical Decomposition” in 1834, little was learned about the electrode–electrolyte interface. The useful Nernst equation and Tafel relationships were developed in 1889 and 1905, respectively, and it was not until the Schrödinger equation was discovered that the groundwork was laid for Gurney's 1931 formulation of a model for electron transfer at the electrochemical interface. Yet things developed slowly until Marcus developed his theory in the 1950s. Applications and generalizations of Gurney's formalism were held back by the absence of powerful computers. This current opinion piece traces through the development of computational models for properties of the electrochemical interface beginning in the 1980s with semiempirical theories that to some extent mimicked Gurney’s formalism, and culminating with recent codes that include all the significant interactions that determine electron transfer reversible potentials and activation energies and their dependencies on the electrode potential. Some theories developed along the way that have restrictions but are still useful are included in the discussion. The writer believes conditions are now set for major advancements in understanding and technology using modern theory in combination with experimental techniques.