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ISRN Physical Chemistry
Volume 2012 (2012), Article ID 841521, 9 pages
http://dx.doi.org/10.5402/2012/841521
Research Article

Visible Light Photocatalysis with Rare Earth Ion-Doped T i O 𝟐 Nanocomposites

1Department of Physics & Electronics, National University of Lesotho, Roma 180, Lesotho
2Department of Chemistry & Chemical Technology, National University of Lesotho, Roma 180, Lesotho

Received 28 September 2011; Accepted 25 October 2011

Academic Editors: J. M. Farrar and P. L. Gentili

Copyright © 2012 Himanshu Narayan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Rare earth (R) ion-doped TiO2 nanocomposites (NCs) with general composition [ R 2 O 3 ] π‘₯ β‹… [ T i O 2 ] 1 βˆ’ π‘₯ (R: Y, Yb, Gd; π‘₯ = 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 ( π‘˜ o b s ) and percent degradation after 180 min ( 𝐢 ξ…ž 1 8 0 ), all NCs produced significantly enhanced degradation as compared to pure TiO2 and PC samples. Best degradation of 95% ( 𝐢 ξ…ž 1 8 0 value) resulted with π‘₯ = 0 . 2 composition of Y3+ doped NC with π‘˜ o b s = 2 . 6 Γ— 1 0 βˆ’ 2  min−1. This was followed by 𝐢 ξ…ž 1 8 0 of 85 and 80%, produced with Yb3+ and Gd3+ doped, π‘₯ = 0 . 1 NCs, at π‘˜ o b s around 1 . 0 Γ— 1 0 βˆ’ 2 and 0 . 9 Γ— 1 0 βˆ’ 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 βˆ’ / h + recombination.