Acetic Acid Adsorption on Anatase TiO2(101)

The adsorption and reactivity of acetic acid on anatase TiO2(101) has been investigated with scanning tunneling microscopy (STM). At low coverage, acetic acid is observed to have a characteristic appearance in STM consistent with a dissociative bidentate binding geometry. At room temperature acetic acid has a relatively strong interaction with the anatase (101) surface and a near-unity sticking probability. When deposited at elevated temperatures (420 K), a saturated coverage displays a partially ordered superstructure with two domains across small regions of the anatase surface. The periodicity of these domains was found to be (2 × 1), again consistent with a bidentate binding geometry of the acetate to two neighboring Ti5c sites along the [010] direction. Heating the acetate-covered surface to 570 K in ultrahigh vacuum resulted in clean desorption of ∼90% of the molecules, leaving only a small fraction undesorbed that were mainly situated at the step edges of the anatase. STM tip pulsing of +6 V was als...