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Abstract Following a renaissance from the 1980s, electrochemistry has developed into sophisticated interdisciplinary science integrating solid‐state and surface science and further, biological sciences. Most remarkably, even the single‐molecule can now be addressed. Single‐molecule electrochemistry covers transition metal complexes, organic redox molecules, fragile biomolecules, and molecular‐scale hybrids between metallic nanoparticles and complex molecules, supported by new theoretical frames. We overview here selected areas of molecular scale electrochemistry. After a theoretical minimum, we address complex molecules in electron transfer, enzyme catalysis, and nanoparticle catalysis. Our focus is on issues not so much previously highlighted, such as competition between superexchange and sequential conduction, and resonance features in the transition between the two limits. Another aspect is coherent multi‐electron transfer for large bias voltages often needed to drive enough current through solute molecular junctions. We note finally some single‐molecule perspectives relating to DNA‐based molecules and to spin transitions via chiral molecules.

The efficiency of corrosion inhibition for waterborne polyurethane based on N-tert-butyl diethanolamine (tB-WPU) is investigated using different techniques. Corrosion weight loss, open circuit potential experiments, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements show that both a commercial reagent and a polyurethane-based inhibitor prevent corrosion at increasing temperature to 50 °C. At 75 °C, the activity of both reagents is reduced. In stirring conditions, the effectiveness of acid corrosion inhibition (25 °C, 500 ppm) drops abruptly from 89.5% to 60.7%, which is related presumably to the complexity of binding the polymer molecules to the metal surface. As follows from thermodynamic calculations, the adsorption of tB-WPU on the metal surface in 2M HCl can be treated as a physisorption. Model quantum–chemical calculations support the experimental studies and elucidate the nature of steel surface–inhibitor molecule chemical bond, which is realized mainly by carboxyl and amino groups. It is concluded that WPUs can be considered as a perspective alternative to commercial oilfield reagents due to their versatility.

Abstract An Fe3+/2+ redox couple in conducting single wall carbon nanotubes filled with water molecules is investigated in the framework of the electron transfer theory and with classical molecular dynamics simulations. The diameter of the nanotubes ranges from 0.8 nm to 3.5 nm. It can be concluded, qualitatively, that the electron transfer rate significantly increases with decreasing nanotube diameter. This effect is explained basically in terms of the solvent reorganization energy. Other factors that can affect the reaction rate are discussed as well.