Ethanol Oxidation Reaction Mechanism on Gold Nanowires from Density Functional Theory

Area of Science:

• * Materials Science
• * Catalysis
• * Computational Chemistry

Background:

• * Thin gold nanowires (NWs) show potential as catalytic supports in chemical reactions.
• * Linear atomic chains (LACs) of gold nanowires (Au-NWs) are investigated for their catalytic activity.
• * The role of impurities in modifying the properties of NWs is crucial for catalytic applications.

Purpose of the Study:

• * To investigate the ethanol oxidation reaction on pure and oxygen-impurity-doped linear atomic chains (LACs) of gold nanowires (Au-NWs).
• * To understand the influence of an oxygen impurity on the structural stability, electronic properties, and reaction pathway of Au-NW LACs during ethanol oxidation.
• * To quantify the effect of the oxygen impurity on the reaction kinetics and activation energy barriers.

Main Methods:

• * Density Functional Theory (DFT) calculations were employed to model and simulate the ethanol oxidation reaction.
• * Two types of linear atomic chains (LACs) were studied: pure Au-NW LACs and Au-NW LACs with an oxygen impurity.
• * Analysis of structural stability, electronic properties, reaction pathways, and activation energy barriers was performed.

Main Results:

• * The oxygen impurity enhances the structural stability of the Au-NW LAC, acting as an anchor for gold atoms.
• * The presence of oxygen modifies the nucleophilic character of the LAC, making it sensitive to its environment.
• * Ethanol oxidation proceeds via two distinct pathways, yielding acetaldehyde (CH3CHO), with oxygen influencing intermediate formation and reaction kinetics.
• * Activation energy barriers are significantly reduced by the oxygen impurity: ~69% in the first stage and ~97% in the second stage.

Conclusions:

• * Oxygen impurities play a critical role in stabilizing gold nanowire linear atomic chains (Au-NW LACs) and modulating their catalytic activity.
• * The presence of oxygen fundamentally alters the reaction mechanism and kinetics of ethanol oxidation on Au-NW LACs.
• * Oxygen-doped Au-NW LACs demonstrate a highly efficient catalytic pathway for acetaldehyde production with substantially lowered energy requirements.