Traces of Potassium Induce Restructuring of the Anatase TiO 2 (001)-(1×4) Surface from a Reactive to an Inert Structure.

Reconstruction of solid surfaces is generally accompanied by changes in surface activities. Here, via a combined experimental and theoretical study, we successfully identified that a trace amount of potassium dopant restructures the mineral anatase TiO 2 (001) single-crystal surface from an added molecule (ADM) termination to an added oxygen (AOM) one without changing the (1×4) periodicity. The anatase TiO 2 (001)-(1×4)-ADM surface terminated with 4-fold coordinated Ti 4c and 2-fold coordinated O 2c sites is (photo)catalytically active, whereas the anatase TiO 2 (001)-(1×4)-AOM surface terminated with O 2c and inaccessible 5-fold coordinated Ti 5c sites is inert. These results unveiled a mechanism of dopant-induced transformation from a reactive to an inert TiO 2 (001)-(1×4) surface, which unifies the existing arguments about the surface structures and (photo)catalytic activity of anatase TiO 2 (001)-(1×4).