Titanium dioxide is a material known mainly for its photocatalytical properties[1] but it has applications in many other fields - the photoelectrochemical (Gr�tzel) cells[2], Li-ion batteries, and possibly in memristors for data storing[3]. While the rutile phase of TiO2 is well investigated in surface science, it is the metastable anatase phase that is used in most applications and generally considered the technologically more relevant polymorph.Surface O vacancies (VO), which form easily on rutile but are not present at anatase(101)[4] are of particular interest for the surface chemistry of this material. In case of anatase(101) the VO's are more stable in the bulk than on the surface. The VO's can be produced on anatase (101) at low temperatures by desorbing surface oxygen atoms by means of bombarding the surface with energetic electrons. The surface VO's migrate to subsurface sites at temperatures as low as 200 K[5].O2 is used as a model molecule to investigate the influence of subsurface VO's on the surface chemistry of the anatase(101). In contrast to rutile(110), the O2 molecule does not dissociate but binds to the surface as a negatively charged dimer. Adsorption of O2 molecules promotes migration of the subsurface VO's back to the surface. It occurs either spontaneously or with help of electric field of the STM tip. Our experiments suggest that the subsurface VO's can be pulled to the surface with electric field of the STM tip, even without presence of adsorbed O2. The work supported by ERC Advanced Research Grant �Oxide Surfaces� [1]       M. A. Henderson, Surf. Sci. Rep. 66 , 185 (2011)[2]       M. Gr�tzel, Nature 414 , 338 (2001)[3]       J.J. Yang et al., Nat. Nanotechnology, 8 , 13 (2013)[4]       Y. He et al., Phys. Rev. Lett. 102  106105 (2009)[5]       P. Scheiber et al., Phys. Rev. Lett., 109 , 136103 (2012)

TiO<sub>2</sub> anatase(101) � (sub)surface oxygen vacancies and O<sub>2</sub> adsorption

246th National Meeting (2013)

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TiO2 anatase(101) � (sub)surface oxygen vacancies and O2 adsorption

TiO₂ anatase(101) � (sub)surface oxygen vacancies and O₂ adsorption