title: Photocatalysis with chromium-doped TiO2: bulk and surface doping.
abstract: The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts.
authors.affiliation: KAUST Catalysis Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia). samy.ouldchikh@kaust.edu.sa.
authors.forename: Samy
authors.initials: S
authors.lastname: Ould-Chikh
authors.forename: Olivier
authors.initials: O
authors.lastname: Proux
authors.forename: Pavel
authors.initials: P
authors.lastname: Afanasiev
authors.forename: Lhoussain
authors.initials: L
authors.lastname: Khrouz
authors.forename: Mohamed N
authors.initials: MN
authors.lastname: Hedhili
authors.forename: Dalaver H
authors.initials: DH
authors.lastname: Anjum
authors.forename: Moussab
authors.initials: M
authors.lastname: Harb
authors.forename: Christophe
authors.initials: C
authors.lastname: Geantet
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Basset
authors.forename: Eric
authors.initials: E
authors.lastname: Puzenat
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D005561:Formates / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D013054:Spectrophotometry, Atomic; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005561:Formates; D002857:Chromium; C030544:formic acid; C009495:titanium dioxide; D014025:Titanium
keywords: chromium; doping; photochemistry; surface chemistry; titanium