Trellises of Molecular Oxygen on Anatase TiO2(101)

The adsorption of molecular oxygen has important implications for the catalytic activity of oxide surfaces, especially for oxidative TiO2 catalysts. In the case of anatase TiO2(101), several studies have noted the importance of surface defects which stabilize the adsorption of oxygen molecules because of charge transfer. Further oxygen adsorption via this mechanism is precluded once a stoichiometric TiO2 surface is attained. Here, the adsorption of oxygen molecules was re-enabled through a simple modification of sample cleaning procedures, resulting in the formation of a well-ordered trellis arrangement of oxygen molecules. The trellis is strongly passivating and does not affect the band gap of the pristine anatase substrate. Furthermore, they induce the extension of anatase terraces up to 100 A wide. The atomic and electronic structures of the trellis were investigated using scanning tunneling microscopy experimentation and density functional theory calculations.