A study on oxygen reduction inhibition at pyridine‐terminated self assembled monolayer modified Au(111) electrodes

Abstract

The electroreduction of oxygen on self-assembled monolayers (SAMs) of various pyridinedisulfides and pyridinethiols on Au(111) surfaces has been investigated in alkaline solutions. Electrochemical experiments that were carried out in threeelectrode cell reveal a good correlation between the chainlength of thiol molecules and the oxygen reduction inhibition of the resulting adlayer films. The effect of retarded diffusion of oxygen through the protective film has been investigated by forming additional layer of immobilized cytochrome c (cyt.c) metalloprotein on pyridine moiety during linear sweep voltammetry (LSV) scans. At sufficiently negative cathodic potentials the electrochemical reaction rate has been observed to increase together with the density of defects. Morphological changes at different levels of cathodic polarization were investigated by ex situ scanning tunneling microscopy (STM), indicating oxygen reduction reaction (ORR) induced structural defects at the metallorganic interface.

Modulation of electrochemical hydrogen evolution rate by araliphatic thiol monolayers on gold

“…In most cases, the rate of an interfacial chemical reaction is reduced by the presence of adsorbates because of their blocking of active sites on the surface, as has been shown, e.g ., for the oxygen reduction reaction (ORR) on Au(111) [9, 12, 13]. If the adsorbate blocks the active sites through covalent bonds, such a rate decrease is also expected for the HER.…”

Influence of dielectric barrier plasma treatment of ZnMgAl alloy‐coated steel on the adsorption of organophosphonic acid monolayers

“…The cathodic electrochemical response was investigated to analyse the defect density and stability of the formed monolayer. 30,31 In the potential range assessed, a diffusion-controlled voltammetric peak around −0.95 V (vs. SHE) preceding the hydrogen evolution reaction (HER) has been detected in all the cases, as can be seen in Figure 3A. The latter can be attributed to oxygen and Zn reduction reactions, which partially overlap.…”

“…Cyclic voltammogrammes were measured in an aerated borate buffer solution to investigate the barrier properties of the as‐prepared ODPA layer. The cathodic electrochemical response was investigated to analyse the defect density and stability of the formed monolayer 30,31 . In the potential range assessed, a diffusion‐controlled voltammetric peak around −0.95 V (vs. SHE) preceding the hydrogen evolution reaction ( HER ) has been detected in all the cases, as can be seen in Figure 3A.…”

“…The latter can be attributed to oxygen and Zn reduction reactions, which partially overlap. While the Zn 2+ electrochemical reduction under similar experimental conditions is characterized by a cathodic peak located around −1.0 V, 9 the onset potential for the oxygen reduction reaction ( ORR ) depends on the nature of the substrate 30 . Both redox processes would be hindered by the presence of a tightly packed monolayer on the metal surface, on the one hand by increasing the overpotentials required for the O 2 /Zn 2+ reduction, and, on the other hand, by decreasing the faradaic currents corresponding to both reduction reactions.…”

Low-Temperature Vapor-Phase Synthesis of Single-Crystalline Gold Nanostructures: Toward Exceptional Electrocatalytic Activity for Methanol Oxidation Reaction

“…In addition, the interface structure between Au NSs and the supporting electrode is critical to the improvement of the electrocatalytic activity since the interface structure significantly affects electron transfer from Au NSs to the conductive substrate and vice versa [18,19,20]. Moreover, clean Au NS surfaces are important to increase the number of effective collisions between reactants and catalytic active sites on the Au NS surface [21,22,23,24]. Thus, an ideal electrocatalytic Au NS should have a well-defined morphology, crystallinity, clean surfaces, and direct interface with a substrate.…”