Why does gold never rust? Its surface may have the clue, Pg2

Key Highlights:

• Gold's resistance to rust and tarnish is attributed to its low reactivity.
• Researchers at Tulane University studied gold surfaces, Au(100) and Au(110), to understand this property.
• Surface reconstruction, where gold atoms rearrange into hexagonal patterns, increases the energy required for oxygen molecules to split.
• Reconstruction suppresses oxidation by nine to twelve orders of magnitude due to atomic geometry.

Detailed Insights:

• Gold's inertness makes it a symbol of permanence, but it's also used as a catalyst in oxidation reactions.
• The study used density functional theory to compare reconstructed and unreconstructed gold surfaces, estimating the energy needed for oxygen dissociation.
• Unreconstructed gold surfaces have a rectangular arrangement of atoms and lower dissociation energy (0.65-0.74 eV).
• Reconstructed surfaces require more than 1 eV for oxygen molecule dissociation, hindering oxidation.
• Stabilizing square or rectangular surface geometries could make gold more reactive in oxidation reactions, potentially improving its catalytic properties.

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Scientific/Technical Concepts Involved:

• Oxidation: A chemical reaction involving the loss of electrons, often resulting in the formation of oxides.
• Catalyst: A substance that speeds up a chemical reaction without being consumed in the process.
• Density Functional Theory: A computational method used to simulate the behavior of atoms and electrons in materials.
• Surface Reconstruction: The rearrangement of atoms on a material's surface to achieve a lower energy state.