The promoting effect of adsorbed carbon monoxide on the oxidation of alcohols on a gold catalyst

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

In heterogeneous catalysis and electrocatalysis, adsorbed carbon monoxide typically acts as a poison or poisoning intermediate in the oxidation of alcohols. However, gold as an (electro)catalyst often exhibits unexpected properties. Here we show that carbon monoxide irreversibly adsorbed on a Au(111) surface in aqueous alkaline media can act as a promoter for the electrocatalytic oxidation of certain alcohols, in particular methanol. In comparison with bare Au(111), the onset potential for methanol oxidation is significantly lower in the presence of adsorbed CO, and formation of the main methanol oxidation products--formaldehyde and formic acid--is enhanced. By studying the effect of adsorbed CO on the oxidation of other alcohols on gold, we conclude that the presence of adsorbed CO promotes beta-hydrogen elimination, that is, C-H bond breaking. Apart from its importance to gold catalysis, this is an unanticipated example of promotion effects by co-adsorbed small molecules in electrocatalysis.

Related collections

Most cited references 27

Record: found
Abstract: found
Article: not found

The role of non-covalent interactions in electrocatalytic fuel-cell reactions on platinum.

J Greeley, Marcia Higuchi, Svetomir N. Markovic … (2009)

The classic models of metal electrode-electrolyte interfaces generally focus on either covalent interactions between adsorbates and solid surfaces or on long-range electrolyte-metal electrostatic interactions. Here we demonstrate that these traditional models are insufficient. To understand electrocatalytic trends in the oxygen reduction reaction (ORR), the hydrogen oxidation reaction (HOR) and the oxidation of methanol on platinum surfaces in alkaline electrolytes, non-covalent interactions must be considered. We find that non-covalent interactions between hydrated alkali metal cations M(+)(H(2)O)(x) and adsorbed OH (OH(ad)) species increase in the same order as the hydration energies of the corresponding cations (Li(+) > Na(+) > K(+) > Cs(+)) and also correspond to an increase in the concentration of OH(ad)-M(+)(H(2)O)(x) clusters at the interface. These trends are inversely proportional to the activities of the ORR, the HOR and the oxidation of methanol on platinum (Cs(+) > K(+) > Na(+) > Li(+)), which suggests that the clusters block the platinum active sites for electrocatalytic reactions.

0 comments Cited 162 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: not found
Article: not found

Catalysis: gold rush.

Masatake Haruta (2005)

0 comments Cited 109 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Enhanced electrocatalysis of the oxygen reduction reaction based on patterning of platinum surfaces with cyanide.

Svetomir N. Markovic, Vojislav R. Stamenkovic, María Esther Escudero … (2010)

The slow rate of the oxygen reduction reaction in the phosphoric acid fuel cell is the main factor limiting its wide application. Here, we present an approach that can be used for the rational design of cathode catalysts with potential use in phosphoric acid fuel cells, or in any environments containing strongly adsorbing tetrahedral anions. This approach is based on molecular patterning of platinum surfaces with cyanide adsorbates that can efficiently block the sites for adsorption of spectator anions while the oxygen reduction reaction proceeds unhindered. We also demonstrate that, depending on the supporting electrolyte anions and cations, on the same CN-covered Pt(111) surface, the oxygen reduction reaction activities can range from a 25-fold increase to a 50-fold decrease. This behaviour is discussed in the light of the role of covalent and non-covalent interactions in controlling the ensemble of platinum active sites required for high turn over rates of the oxygen reduction reaction.