Steps on anatase TiO2(101)

X.-Q. Gong, A. Selloni, M. Batzill, U. Diebold

Department of Chemistry, Princeton University, Princeton, NJ 08544, U.S.A.
Department of Physics, Tulane University, New Orleans, Louisiana 70118, U.S.A.

Nature Mater. 5 (2006) 665-670

Surface defects strongly influence the surface chemistry of metal oxides, and a detailed picture of defect structures may help to understand reactivity and overall materials performance in many applications. We report first-principles calculations of step edges, the most common intrinsic defects on surfaces (and probably the predominant ones on nanoparticles). We have determined the structure, energetics, and chemistry of step edges on the (101) surface of TiO2 anatase, an important photocatalytic material. Scanning tunnelling microscopy measurements of step-edge configurations and the contrast in atomically resolved images agree remarkably well with the theoretical predictions. Step-edge formation energies as well as the adsorption energies of water scale with the surface energy of the step facet, a trend that is expected to generally hold for metal oxide surfaces. Depending on the terrace/step configuration, this can lead to a situation where a step is less reactive than the flat terrace.

Reprints available from U. Diebold (diebold at iap_tuwien_ac_at).

Users with online access to Nature Materials can load the article from the publisher.