Lanthanide oxide-doped titanium dioxide: effective photocatalysts for the degradation of organic pollutants

A series of lanthanide oxide-doped titanium dioxide photocatalysts Ln₂O₃/TiO₂ (Ln³⁺ = Eu³⁺, Pr³⁺, Yb³⁺) were prepared. The photocatalysts reveal a substantially enhanced activity for the degradation of organic pollutants, as compared to undoped TiO₂. The photodegradation processes of p-nitrobenzoic acid, (1), p-chlorophenoxyacetic acid, (2), aniline, (3), salicylic acid, (4), and trans-cinnamic acid, (5), with the different photocatalysts was examined. The photodegradation of (1)-(5) is significantly faster with Ln₂O₃/TiO₂ photocatalysts and leads to complete mineralization of the organic compounds. The high activity of the Ln₂O₃/TiO₂ photocatalysts is attributed to the enhanced association of the functionalized organic pollutants to lanthanide-ion surface sites.