Visible Light Photocatalysis with Rare Earth Ion-Doped TiO2 Nanocomposites

Abstract EN

Rare earth (R) ion-doped TiO2 nanocomposites (NCs) with general composition [R2O3]x⋅[TiO2]1-x (R: Y, Yb, Gd; x=0.1, 0.2) were synthesized through co-precipitation/hydrolysis (CPH).

NC particles with average size of approximately a few tens of nm were obtained.

Similar compositions of polycrystalline (PC) samples with larger particle size were also prepared employing solid state reaction (SSR) method.

Visible light photocatalytic activity of all samples was investigated for degradation of Congo red (CR) dye.

Both in terms of apparent rate constant (kobs) and percent degradation after 180 min (C180′), all NCs produced significantly enhanced degradation as compared to pure TiO2 and PC samples.

Best degradation of 95% (C180′ value) resulted with x=0.2 composition of Y3+ doped NC with kobs=2.6×10−2 min−1.

This was followed by C180′ of 85 and 80%, produced with Yb3+ and Gd3+ doped, x=0.1 NCs, at kobs around 1.0×10-2 and 0.9×10-2 min−1, respectively.

The observations clearly suggest that enhanced photocatalytic degradation of CR is directly related to smaller particle size of the catalysts.

Moreover, the presence of rare earth ions in the composites facilitates further improvement of degradation efficiency through effective suppression of e-/h+ recombination.