title: Solid-state NMR and EPR analysis of carbon-doped titanium dioxide photocatalysts (TiO(2-)(x)C(x)).
abstract: Carbon-doped TiO(2) have received attention recently because of their potential for environmental photocatalysis and solar hydrogen conversion applications. Three different carbon-doped TiO(2) nanoparticle materials were synthesized via sol-gel and hydrothermal procedures, and analyzed by (13)C solid-state nuclear magnetic resonance (SSNMR) and other methods to characterize the environment of the doping species. UV/vis spectra and powder X-ray diffraction (XRD) patterns showed that the synthesized materials absorbed visible light and their crystal structures corresponded to anatase. (13)C SSNMR analyses of TiO(2-)(x)C(x) displayed signals corresponding to carbonate-type or sp(2)-type carbon species. Variable contact CP-MAS and dipolar dephasing analyses gave evidence for the presence and proximity of H atoms near these carbonate species. Electron paramagnetic resonance (EPR) spectroscopy showed that the thermally oxidized TiO(2-)(x)C(x) displayed a complex mixture of point defects, electron and hole trapping centers, all attributable to the incorporation of carbon, while the XPS data ruled out the presence of carbide species.
authors.affiliation: Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, IN 47907, USA.
authors.forename: Enrique A
authors.initials: EA
authors.lastname: Reyes-Garcia
authors.forename: Yanping
authors.initials: Y
authors.lastname: Sun
authors.forename: Karla R
authors.initials: KR
authors.lastname: Reyes-Gil
authors.forename: Daniel
authors.initials: D
authors.lastname: Raftery
mesh_terms: D002244:Carbon / Q000032:analysis* / Q000737:chemistry*; D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry; D055668:Photochemical Processes; D014025:Titanium / Q000032:analysis* / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D002244:Carbon; D014025:Titanium