Sacrificial water photolysis on TiO2 and SrTiO2 fine powders under bond gap irradiation

Abstract

Surface hydroxylation is not the only criterion for obtaining higher catalytic activity in water photolysis mediated by TiO?. Neutralization of surface hydroxyls on TiO? by alkali may produce Ti–O groups, which trap photogenerated holes to form Ti–O• radicals and subsequently peroxotitanium species at the surface, leading to the evolution of O? [118].

The presence of crystallographic defects on particles with poor crystallinity, prepared by alternative routes, may broaden the energy states of Ti–O•. The resulting surface state “bands” can enable hole transfer to species in solution, such as O?/OH?. In contrast, for monocrystalline particles free of defects, the corresponding surface states may have minimal energy spread, so charge transfer is possible only to hole scavengers such as EDTA or TEOA.

Platinized rutile powders are found to be equally active as anatase in sacrificial systems.