Cerium doped zirconium dioxide as a potential new photocatalytic material. The role of the preparation method on the properties of the material

Small amounts of Ce4+ ions dispersed in the bulk of ZrO2 give to this material unexpected properties of photoactivity under visible light. Three different samples have been synthesized following different methods and using different precursors and all show some degree of photoactivity. This has been monitored via EPR spectroscopy in terms of charge separation (electrons and holes formation) under polychromatic light having lambda > 420 nm. This behaviour, unimaginable for bare zirconia due to the large band gap of this oxide (around 5 eV), is possible because of the presence in the solid of empty 4f Ce states located in the middle of the band gap which act as intermediate levels in a double excitation mechanism. The doped oxide here described can be considered an example of third generation photoactive material operating under visible light. (C) 2015 Elsevier B.V. All rights reserved.