We have carried out a periodic Kohn-Sham density functional theory investigation of the pathways by which carbon-carbon bonds could be formed during the electrochemical reduction of CO2 on Cu(100) using a model that includes the effects of the electrochemical potential, solvent, and electrolyte. The electrochemical potential was set by relating the applied potential to the Fermi energy and then calculating the number of electrons required by the simulation cell for that specific Fermi energy. The solvent was included as a continuum dielectric, and the electrolyte was described using a linearized Poisson-Boltzmann model. The calculated potential of zero charge for a variety of surfaces agrees with experiment to within a mean average error of 0.09 V, thereby validating the assumptions of the model. Analysis of the mechanism for C-C bond formation revealed that at low-applied potential, C-C bond formation occurs through a CO dimer. However, at high applied potentials, a large activation barrier blocks this pathway; therefore, C-C bond formation occurs through reaction of adsorbed CHO and CO. Rate parameters determined from our calculations were used to simulate the kinetics of ethene formation during the electrochemical reduction of CO over a Cu(100) surface. An excellent match was observed between previously reported measurements of the partial current for ethene formation as a function of applied voltage and the variation in the partial current for C-C bond formation predicted by our microkinetic model. The electrochemical model reported here is simple, fairly easy to implement, and involves only a small increase in computational cost over calculations neglecting the effects of the electrolyte and the applied field. Therefore, it can be used to study the effects of applied potential and electrolyte composition on the energetics of surface reactions for a wide variety of electrochemical reactions.

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Identification of Possible Pathways for C-C Bond Formation during Electrochemical Reduction of CO2: New Theoretical Insights from an Improved Electrochemical Model.

Oxygen electroreduction on Ag(111) : The pH effect

The first results of a study of the oxygen reduction reaction on a rotating ring−disk electrode using single-crystal Pt disk electrodes in alkaline solution are presented The order of activity of Pt(hkl) in 01M KOH increased in the sequence (100) < (110) < (111) for both oxygen and peroxide reduction These differences are attributed to the structure sensitivity of hydroxyl anion (OH-) adsorption on Pt(hkl) and its inhibiting (site blocking) effect on oxygen kinetics Two different types of OHads occur on Pt(100) and Pt(110), a reversible OHrv, and an irreversible OHir, while only the reversible form is formed on Pt(111) Very small fluxes (I R/N ≪ 001I D) of peroxide were detected at the ring at potentials where the surfaces have only the reversible form of OHads More peroxide (I R/N < 003I D) was found with the Pt(100) and Pt(110)surfaces in the potential region where irreversible adsorption occurs The mechanism of O2 reduction was also affected by adsorbed hydrogen with increased formation of per

Oxygen reduction on silver low-index single-crystal surfaces in alkaline solution: rotating ring disk(Ag(hkl)) studies.

Structure of the metal/electrolyte solution interface: new data for theory

In situ infrared visible sum frequency generation spectroscopy (SFG) is used to examine the structure of water at the Ag-water interface in NaF and KF electrolyte solutions. Water is observed in environments associated with both the electrode surface and the diffuse double layer. Peaks are observed that are correlated with low-order water, water interacting with electrolyte ions, specifically adsorbed water to the electrode surface, and hydronium. Spectra obtained from a thiol-modified Ag surface enabled discrimination between surface-bound water and that in the double layer. The water organization is dependent on applied potential, with the observed intensities for specifically adsorbed and ion solvating water diminishing near the pzc.

L. Doubova

Papers

The temperature dependence of the double layer parameters of the (111) face of silver

The dependence of the potential of zero charge of silver electrodes on the crystallographic orientation of the surface

Influence of the crystallographic orientation of the surface on the potential of zero charge of silver electrodes

Specific adsorption of fluoride ions on the (110) face of a silver single crystal electrode

The temperature coefficient of the potential of zero charge of the (110) face of silver