title: A potential site for trapping photogenerated holes on rutile TiO(2) surface as revealed by EPR spectroscopy: an avenue for enhancing photocatalytic activity.
abstract: Rutile TiO(2) nanoparticles with new sites for effectively trapping photogenerated holes have been prepared by reacting the TiO(2) nanoparticles prepared in hydrogen atmosphere with molecular oxygen at elevated temperatures. The observed g values and the occurrence of (47)Ti and (49)Ti octet hyperfine pattern allowed us to assign this EPR active center to surface oxygen centered anion radical with two coordinating titaniums. The effective trapping of photogenerated holes by these new sites inhibits the electron-hole recombination and results in an enhanced photocatalytic activity under visible light by a factor of 2.5 compared with samples prepared parallel in air. Oxidation of reduced TiO(2) apparently is a simple low-cost and promising route for improving the photoactivity of TiO(2).
authors.affiliation: Physics Department and Nanotechnology Research Center, National Dong Hwa University, Hualien, Taiwan 97401.
authors.forename: Neeruganti O
authors.initials: NO
authors.lastname: Gopal
authors.forename: Hsin-Hsi
authors.initials: HH
authors.lastname: Lo
authors.forename: Shiann-Cherng
authors.initials: SC
authors.lastname: Sheu
authors.forename: Shyue-Chu
authors.initials: SC
authors.lastname: Ke
mesh_terms: D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D008027:Light; D055668:Photochemical Processes; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D014025:Titanium