Effect of rare earth doping on the enhancement of photocatalytic performance of ceria nanocrystals under natural sunlight
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The photocatalytic properties of CeO2, Gd:CeO2 and Sm:CeO2 nanocrystals have been investigated under natural sunlight. The structural and morphological analyses of the synthesized samples were carried out by X-ray powder diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The UV–Vis absorption of pure and doped ceria confirmed the reduction in the band gap values. Fluorescence spectra of CeO2 show strong emission peaks variation at 424 and 466 nm and for rare earth doped ceria at 466 nm. XPS analysis revealed in the composition, Ce4+ to Ce3+ ratio and energy states of the prepared samples. The photocatalytic performance of Sm:CeO2 was relatively high compared to pure and Gd:CeO2 in the degradation of methylene blue dye. The variation in the photocatalytic performance was discussed based on the oxygen vacancy and Ce3+ concentrations. The present study confirmed that the incorporation of rare earth ions increased the oxygen vacancies, which caused changes in Ce4+/Ce3+ ratio thereby enhancing the visible photocatalytic activities.
One of the authors M. Karl Chinnu is grateful to Prof. Forest Shish-Sen Chien, Department of Applied Physics, Songhai University and Ministry of Taiwan Government for Postdoctoral fellowship. The authors are thankful to Nanomaterials laboratory, Research Institute of Electronics, Shizuoka University, Japan for HR-TEM and XPS studies.
- 1.L. Chen, J. Tina, H. Quid, Ceram. Int. 13, 3422 (2009)Google Scholar