Khaberni - Chemists from the United States have discovered that gold does not oxidize due to the air's oxygen because it is extremely inert, thanks to the unique arrangement of its atoms on its surface, arranged in a hexagonal honeycomb structure.
According to the journal Physical Review Letters, scientists explain that this pattern of gold atoms slows its oxidation by more than a billion times.
A team of American chemists led by Associate Professor Matthew Montemore at Tulane University reached this conclusion while studying why gold is the most inert of metals, even though its nanoparticles undergo a wide range of reactions. However, even in such cases, gold shows relative resistance to absorbing oxygen at low temperatures and pressures, which limits its use in catalytic chemistry.
The researchers say, "Our experiments have shown that the hexagonal structure of gold's surface forms a strong barrier that slows the penetration of oxygen atoms several orders of magnitude compared to the arrangement of gold atoms in squares or parallelograms. If gold did not naturally form in these hexagonal shapes, it would oxidize very quickly in the air."
To uncover the reasons for this, researchers used quantum chemistry methods to calculate the interactions between oxygen molecules and the different "patterns" that gold atoms could form on its surface. The results showed that gold atoms are capable of forming two types of hexagonal structures, each of which forms a very strong barrier against the penetration and decomposition of oxygen molecules into individual atoms.
The researchers discovered that oxygen actively penetrates gold when its atoms are arranged in squares or rectangles, which leads to its oxidation at a rate a billion times faster. However, this does not occur often because the surface of the gold restructures itself most of the time, acquiring a structure that makes it highly resistant to oxygen.
According to the researchers, this process does not occur in certain types of nanoparticles, which are supposed to contain so few gold atoms that their surface cannot rearrange and become resistant to oxygen. This explains why they react effectively with oxygen, which could be used in developing new catalysts.
