The interaction of H
2O molecules with various oxide surfaces were investigated by using middle-infrared (MIR) and near-infrared (NIR) spectroscopies. The physicochemical properties of oxide surfaces such as hydrophilicity or hydrophobicity were then discussed from the viewpoint of the intermolecular hydrogen bonds in the H
2O clusters. SiO
2 surface showed hydrophobic property as compared to TiO
2 or Al
2O
3 surfaces. However, smaller amount of H
2O molecules on SiO
2 surface can easily spread out to form H
2O thin layer due to small contribution of intermolecular hydrogen bonds in the H
2O clusters. As a result, such hydrophobic SiO
2 surface shows high wettability. On the other hand, TiO
2 or Al
2O
3 surfaces adsorbed large amounts of H
2O and hydrocarbons because such polar molecules preferentially interact with such cationic (Ti
4+ or Al
3+) sites, showing both hydrophilic and oleophilic properties. However, larger amount of H
2O molecules on the TiO
2 or Al
2O
3 surfaces strongly interacted with each other to form aggregated bulky H
2O clusters on the surfaces. As a result, such hydrophilic surfaces show low wettability.
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