Cerium-modified TiO2 nanocrystalline films for visible light photocatalytic activity

Nanoscale TiO2 films and their application in remediation of organic pollutants

“…These methods include sol-gel, chemical vapor deposition, hydrothermal, electrophoretic deposition, flame-aerosol, sputtering deposition, and spray pyrolysis [27,84,92,[107][108][109][110][111]. Below, each method is summarized for the preparation of photocatalyst nanoparticles and thin films of TiO 2 while Table 1 summarizes the relative merits and demerits of each technique for comparative purposes.…”

“…As such, TiO 2 catalysts have been prepared in various nano-forms such as mobilized (nanoparticle powders [65], nanowires [79], nanotubes [32,80,81], and nanorods [82,83] in suspension form) and immobilized states (as thin films) [3,28,37,[84][85][86][87], with each having its own advantages and disadvantages. For example, as nanopowder mobilized form, TiO 2 has high photocatalytic activity because of its large available sur-A c c e p t e d M a n u s c r i p t Edited June 15 7 face area for photocatalysis [27,88]. However, they can potentially agglomerate in their suspension form thus reducing their activity as well as their potential for recyclability.…”

“…Many different metals, such as Pt, Pd, Ag, Sr, Au, Ce, V, have been employed for the preparation of metal doped TiO 2 films [27,86,91,[117][118][119][120][121][122][123][124][125]; some representative studies towards their preparation are briefly discussed below.…”

“…Highly porous nanostructured Ce-modified TiO 2 thin films were synthesized for visible light utilization via high temperature sol-gel dip coating process on borosilicate glass substrates [27].…”

“…Despite the widespread usefulness of TiO 2 as a photocatalyst in water treatment for pollutant destruction, there are two major constraints that limit its photocatalytic efficiency: (1) only 3-5% of whole solar spectrum (UV region) is used efficiently for the photocatalysis process because of the large band-gap of conventional TiO 2 (3.2 eV for anatase phase) and (2) fast recombination of photo-generated electron-hole pairs occurs during TiO 2 photocatalysis [27]. Therefore, it has become imperative to improve TiO 2 photocatalytic efficiency by extending its absorption threshold from the UV-light region to the visible-light region which comprises a larger portion of the solar spectrum in terms of energy availability ( 45% of solar light) and reducing the rate of recombination of the photo-generated electron/hole pairs [28][29][30].…”