The Influence of Chemisorbed Organic Monolayers on Electrode Surface Oxidation

Abstract The chemisorption at monolayer coverages of various organic molecules from aqueous solutions onto smooth polycrystalline electrodes and the resistance of the resulting monolayers towards electrochemical oxidation have been studied. This survey represents the preliminary stage in a series of investigations aimed at better understanding, at the atomic level, of metal passivation by monolayer organic films. The electrodes studied (Rh, Pd, Ir, Pt, and Au) are those whose anodic dissolution is preceded by surface-oxide formation. For these metals, corrosion resistance can be associated with the retardation of the surface oxidation; hence, the extent of surface-oxide retardation is one measure of the passivation characteristics of an organic monolayer. Thirty-eight organic compounds containing at least one surface-active functional group were investigated: alkenes, alkynes, aromatics, heterocyclic aromatics, alcohols, phenols, sulfides, amines, amides, nitriles, CO, aldehydes, carboxylates, esters, and...