Photocatalytic reduction of oxygen molecules at the (1 0 0) TiO 2 anatase surface

Abstract

The adsorption, photoreduction and chemical activity of oxygen molecules on the (1 0 0) anatase surface have been investigated here together with the effects that surface oxygen vacancies (V O) can have on these O 2-related processes. We use an original approach by treating molecules on the TiO 2 surface like surface defects in the same framework successfully used for defects in semiconductors. The achieved results: (i) give the first theoretical evidence of an acceptor behaviour of an adsorbed O 2 molecule, which is at the origin of its photoreduction; (ii) show that the V O donor character is strongly affected by the interaction with O 2; and (iii) suggest that the release of O 2 - 1 radicals as well as the formation of O 2-related radicals may be favoured by photogenerated electrons in presence of surface V O’s.