Origins of Less Noble Behavior by Au during CO Adsorption

Abstract

The behavior of the CO interaction with gold in an electrochemical environment is presented in this work by means of the SERS technique. The results show spectroscopic evidence that the adsorbed CO promotes the formation of oxidic species even at potentials where it is not thermodynamically favorable (lower than 0.6 V vs RHE), explaining the low-overpotential CO electrooxidation reaction onset (@ ca. 0.2 V). At high potentials (<1.3 V), the CO displays an anomalous behavior, persisting adsorbed on the surface at the high coverage oxide film, which allows us to use the CO molecule as a probe and get information about the electrode surface on the course of the reaction as well as suggests gold oxide to be an active catalyst in small organic alcohol oxidation.

Octahedral gold-silver nanoframes with rich crystalline defects for efficient methanol oxidation manifesting a CO-promoting effect

“…This set of experiments clearly illustrate while CO is poisonous for Pt, it actually promotes the MOR on Au 3 Ag NFs. Similar CO-promoting behavior on the Au (111) surface was also observed by Rodriguez et al, who attributed the enhanced reactivity to the enhancement in electrostatic OH − bonding, as a result of the change in electrostatic surface potential (work function) when CO is adsorbed atop the gold surface 34,57,58 . We note that these observations are conceptually analogous to the homogeneous electrocatalysis catalyzed by organometallics, of which the catalytic properties of the active metal center can be tuned by tailoring its coordination with organic ligands, such as the Monsanto and Cativa processes using CO as the ligand 59,60 .…”

An Overview of Glycerol Electrooxidation Mechanisms on Pt, Pd and Au

“…Nevertheless, this feature prevents both the poisoning effect (CO existing as CO [102] ) and the formation of Au‐OH(ads) [103] . It is noticeable that the poisoning effect reportedly plays a positive role on the efficiency of Au‐GEOR [possibly due to the promotion of OH(ads) formation on Au(111) and Au(100) by CO(ads)] [104–107] This is supported by an experiment carried out using SERS to monitor CO(ads) on Au electrode, showing that the onset potential of OH(ads) formation becomes much lower in the presence of CO(ads) [108] . The researchers proposed that the potential of zero charge (PZC) for Au is shifted downward by CO(ads) so that the formation of OH(ads) is promoted.…”

Potential-Dynamic Surface Chemistry Controls the Electrocatalytic Processes of Ethanol Oxidation on Gold Surfaces

“…Here, our in situ liquid SIMS observations justified with solid molecular evidence that the potential-dynamic formation and evolution of the adsorbed hydroxide intermediates Au­(OH) ads on gold surfaces played a mandatory catalytic role and controlled the electro-oxidation of ethanol in alkaline solutions. Moreover, it was reported that in the case of electro-oxidation of carbon monoxide (CO) on gold surfaces the cooperative process of CO and OH – adsorption led to enhanced reactivity. ,− The adsorption of both negatively charged species on the gold surface would not lead to a repulsive interaction but instead results in the upward shift of the Au d band toward the Fermi level, which facilitates charge transfer between the adsorbed species and metal surfaces . This might also explain the catalytic mechanism of ethanol electro-oxidation in this system, as discussed above.…”