Traces of Potassium Induce Restructuring of the Anatase TiO2(001)-(1x4) 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 TiO2(001) single-crystal surface from an added molecule (ADM) termination to an added oxygen (AOM) one without changing the (1x4) periodicity. The anatase TiO2(001)-(1x4)-ADM surface terminated with 4-fold coordinated Ti-4c and 2-fold coordinated O-2c sites is (photo)catalytically active, whereas the anatase TiO2(001)-(1x4)-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 TiO2(001)-(1x4) surface, which unifies the existing arguments about the surface structures and (photo)catalytic activity of anatase TiO2(001)-(1x4).

Automated summary

A trace amount of potassium dopant is found to restructure the surface of anatase TiO2(001) single crystal, changing the termination from molecule termination to oxygen termination. The molecule-terminated surface shows (photo)catalytic activity, while the oxygen-terminated surface is inert.