Study of electronic state of supported gold nanospecies by IR spectroscopy

The nature of different Au species supported on hexagonal mesoporous silica has been studied by infrared spectroscopy of adsorbed CO. Experiments revealed existence of the following states of supported gold: neutral metal particles Au°, ions Au
⁺
and a number of partly charged states Au
^δ+
with different effective charge. Redox pretreatments (vacuum, O
₂
and H
₂
) of Au/SiO
₂
at the different temperatures (100, 300 and 500°C) exert a significant effect on the electronic state of supported Au species. The experiments showed high stability of Au
^δ+
states under all treatments; that may prove their active role in catalytic properties of gold.