Can an electrode reaction occur without electron transfer across the metal/solution interface?

Interaction of Bis-(sodium-sulfopropyl)-Disulfide and Polyethylene Glycol on the Copper Electrodeposited Layer by Time-of-Flight Secondary-Ion Mass Spectrometry

The interactions of the functional additives SPS (bis-(sodium-sulfopropyl)-disulfide) and polyethylene glycol (PEG) in the presence of chloride ions were studied by time-of-flight secondary-ion mass spectrometry (TOF-SIMS) in combination with cyclic voltammetry measurements (CV). The PEG, thiolate, and chloride surface coverages were estimated and discussed in terms of their electrochemical suppressing/accelerating abilities. The conformational influence of both the gauche/trans thiolate molecules, as well as around C-C and C-O of PEG, on the electrochemical properties were discussed. The contribution of the hydrophobic interaction of -CH₂-CH₂- of PEG with chloride ions was only slightly reduced after the addition of SPS, while the contribution of Cu-PEG adducts diminished strongly. SPS and PEG demonstrated significant synergy by significant co-adsorption. It was shown that the suppressing abilities of PEG that rely on forming stable Cu-PEG adducts, identified in the form C₂H₄O₂Cu⁺ and C₃H₆OCu⁺, were significantly reduced after the addition of SPS. The major role of thiolate molecules adsorbed on a copper surface in reducing the suppressing abilities of PEG rely on the efficient capture of Cu²⁺ ions, diminishing the available copper ions for the ethereal oxygen of PEG.

Lithium Diffusion in Copper

Copper is the conventional, broadly applied anode current collector in lithium-ion batteries, because Li does not form intermetallic alloys with Cu at room temperature. Fast diffusion and trapping of lithium in copper were, however, suggested in the past, and the involved diffusion mechanisms are still not clarified. By using three complementary methods, we determine grain boundary and lattice diffusion of lithium in copper. We show that indiffusion into copper is possible not only from metallic lithium deposits at the surface but also from a Li⁺-containing electrolyte. Lattice diffusion (D₀ = 3.9 × 10^-9 cm²/s; E_a = 0.68 eV) and grain boundary diffusion (D₀ = 1.5 × 10^-11 cm²/s; E_a = 0.36 eV) are found to be 13 orders of magnitude lower than previously published. Furthermore, for practical Li-ion battery considerations, lithium trapping in copper current collectors, which relies heavily on operating temperature and morphology, is discussed.

Parallel- and serial-contact electrochemical metallization of monolayer nanopatterns: A versatile synthetic tool en route to bottom-up assembly of electric nanocircuits

Contact electrochemical transfer of silver from a metal-film stamp (parallel process) or a metal-coated scanning probe (serial process) is demonstrated to allow site-selective metallization of monolayer template patterns of any desired shape and size created by constructive nanolithography. The precise nanoscale control of metal delivery to predefined surface sites, achieved as a result of the selective affinity of the monolayer template for electrochemically generated metal ions, provides a versatile synthetic tool en route to the bottom-up assembly of electric nanocircuits. These findings offer direct experimental support to the view that, in electrochemical metal deposition, charge is carried across the electrode-solution interface by ion migration to the electrode rather than by electron transfer to hydrated ions in solution.

Atomistic Modeling of Corrosion Events at the Interface between a Metal and Its Environment

Atomistic simulation is a powerful tool for probing the structure and properties of materials and the nature of chemical reactions. Corrosion is a complex process that involves chemical reactions occurring at the interface between a material and its environment and is, therefore, highly suited to study by atomistic modeling techniques. In this paper, the complex nature of corrosion processes and mechanisms is briefly reviewed. Various atomistic methods for exploring corrosion mechanisms are then described, and recent applications in the literature surveyed. Several instances of the application of atomistic modeling to corrosion science are then reviewed in detail, including studies of the metal-water interface, the reaction of water on electrified metallic interfaces, the dissolution of metal atoms from metallic surfaces, and the role of competitive adsorption in controlling the chemical nature and structure of a metallic surface. Some perspectives are then given concerning the future of atomistic modeling in the field of corrosion science.