Tuning the Stability of Surface Intermediates Using Adsorbed Oxygen: Acetate on Au(111)

Abstract

Selective oxidative reactions promoted by gold depend critically on controlling the coverage and stability of adsorbed intermediates, as well as promoting specific bond activations of those intermediates. We demonstrate that acetate, a common intermediate in the oxidation of olefins, aldehydes, and alcohols, is destabilized by 7-10 kcal/mol by coadsorbed oxygen relative to its stability on the clean gold surface. The amount of destabilization depends on the oxygen coverage. Peak temperatures of products indicative of oxygen-assisted and clean-surface bond activation differ by up to 130 K. Experiments with d3-acetate show a kinetic isotope effect of 6.9 at 400 K, indicating that the rate-limiting step of the low temperature oxygen-assisted reaction is γ-CH bond breaking. This clearly demonstrates that coadsorbed oxygen activates γ-CH bonds on gold and suggests that an oxygen-assisted activation may also occur for β-CH bonds crucial in oxygen-assisted alcohol coupling on metallic gold catalysts, as predicted by theory.

Adsorption of Acetate on Au(111): An in‐situ Scanning Tunnelling Microscopy Study and Implications on Formic Acid Electrooxidation

“…The electrosorption of anions, in particular oxoanions and halides on noble metal electrode surfaces, is a major topic in the field of interfacial electrochemistry and electrocatalysis. The presence of adsorbed species and their adsorption strength can strongly affect reaction kinetics, activity and selectivity . Electrocatalytic reactions are often influenced by nonreactive specifically adsorbed anions (spectator species), that lead to changes in structure and composition of the electrical double‐layer and alter the electronic properties of a catalyst's surface or even block active surface sites .…”

Shape Control in Gold Nanoparticles by N-Containing Ligands: Insights from Density Functional Theory and Wulff Constructions

“…Gold chemistry has intrigued scientists in both homogeneous and heterogeneous catalysis for more than two decades now [1][2][3][4]. Particularly, when prepared highly porous, the catalytic activity is more prominent likely due to the presence of a larger fraction of low coordinated sites [5][6][7][8]. Most of the mechanisms for the reactivity on clean metals or organometallic compounds have been clarified [9] but there is still a wide open area regarding ligand coated nanoparticles that might abridge the properties between the two materials.…”

Self-assembly of acetate adsorbates drives atomic rearrangement on the Au(110) surface

“…1 ). Carboxylates lead to undesirable combustion to CO 2 in catalytic oxidation reactions 11 12 13 14 15 , and at the same time are possible intermediates in the reverse process of CO 2 reduction 16 17 .…”