Ethanol Oxidation Reaction Mechanism on Gold Nanowires from Density Functional Theory

• Published in: Chemphyschem Vol. 24; no. 6; pp. e202200723 - n/a
• Main Authors: Bueno, O. V. M., San‐Miguel, M. A., Silva, E. Z.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 14.03.2023
• Subjects: Acetaldehyde; Chemical reactions; density functional calculations; Density functional theory; Ethanol; ethanol oxidation; Gold; gold nanowire; Impurities; linear atomic chain; molecular dynamics; Nanowires; Oxidation; Oxygen; Reaction intermediates; Reaction mechanisms; Structural stability; linear atomic chain; density functional calculations; ethanol oxidation; molecular dynamics; gold nanowire
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.202200723

Thin gold nanowires (NWs) are materials that could be used as support in different chemical reactions. Using density functional theory (DFT) it was shown that NWs that form linear atomic chains (LACs) are suitable for stimulating chemical reactions. To this end, the oxidation reaction of ethanol supported on the LACs of Au−NWs was investigated. Two types of LACs were used for the study, one pure and the other with an oxygen impurity. The results showed that the oxygen atom in the LAC fulfills important functions throughout the reaction pathway. Before the chemical reaction, it was observed that the LAC with impurity gains structural stability, that is, the oxygen acts as an anchor for the gold atoms in the LAC. In addition, the LAC was shown to be sensitive to disturbances in its vicinity, which modifies its nucleophilic character. During the chemical reaction, the oxidation of ethanol occurs through two different reaction paths and in two stages, both producing acetaldehyde (CH3CHO). The different reaction pathways are a consequence of the presence of oxygen in the LAC (oxygen conditions the formation of reaction intermediates). In addition, the oxygen in the LAC also modifies the kinetic behavior in both reaction stages. It was observed that, by introducing an oxygen impurity in the LAC, the activation energy barriers decrease ∼69 % and ∼97 % in the first and second reaction stages, respectively. Oxidation reaction of ethanol stimulated by Au nanowires (Au−NW) is reported. Using density functional calculations, two NWs are studied, one with a linear atomic chain (LAC) of four Au atoms and another one with an oxygen impurity inserted in the LAC. It is shown that although the reaction occurs around the Au atoms, the NW with O impurity has a lower activation barrier, which accelerates the reaction to produce acetaldehyde (CH3CHO).