FTIR study of nanosized gold on ZrO2 and TiO2

A FTIR study at low temperature on nanosized gold dispersed on ZrO2 and on TiO2 has been performed. The average size of gold particles (4.1 ± 0.5 nm) is the same on both the supports, nevertheless CO and O2 adsorption and interactions evidenced some differences between the two samples. At 90 K, the absorption bands of CO adsorbed on gold fall at the same frequencies in both the samples, but the CO molecule gives rise to a kind of back spillover mechanism from the support to the metal, when gold is dispersed on TiO2. This behaviour is not observed on Au/ZrO2, where CO is less strongly adsorbed on gold. The CO–O2 reactivity is very different: no reaction takes place at 90 K on Au/ZrO2, while CO2 is immediately observed on Au/TiO2. The differences are discussed on the basis of structural and electronic differences in the gold–support interactions.