title: Controlling surface defects and photophysics in TiO2 nanoparticles.
abstract: Titanium dioxide (TiO2) is widely used for photocatalysis and solar cell applications, and the electronic structure of bulk TiO2 is well understood. However, the surface structure of nanoparticulate TiO2, which has a key role in properties such as solubility and catalytic activity, still remains controversial. Detailed understanding of surface defect structures may help explain reactivity and overall materials performance in a wide range of applications. In this work we address the solubility problem and surface defects control on TiO2 nanoparticles. We report the synthesis and characterization of ∼4 nm TiO2 anatase spherical nanoparticles that are soluble and stable in a wide range of organic solvents and water. By controlling the temperature during the synthesis, we are able to tailor the density of defect states on the surface of the TiO2 nanoparticles without affecting parameters such as size, shape, core crystallinity, and solubility. The morphology of both kinds of nanoparticles was determined by TEM. EPR experiments were used to characterize the surface defects, and transient absorption measurements demonstrate the influence of the TiO2 defect states on photoinduced electron transfer dynamics.
authors.affiliation: Department of Chemistry and Biochemistry, Center for Bioenergy and Photosynthesis, Arizona State University , Tempe, Arizona 85287-1604, United States.
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Llansola-Portoles
authors.forename: Jesse J
authors.initials: JJ
authors.lastname: Bergkamp
authors.forename: Daniel
authors.initials: D
authors.lastname: Finkelstein-Shapiro
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Sherman
authors.forename: Gerdenis
authors.initials: G
authors.lastname: Kodis
authors.forename: Nada M
authors.initials: NM
authors.lastname: Dimitrijevic
authors.forename: Devens
authors.initials: D
authors.lastname: Gust
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Moore
authors.forename: Ana L
authors.initials: AL
authors.lastname: Moore
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D004735:Energy Transfer; D053768:Metal Nanoparticles / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D055668:Photochemical Processes; D012995:Solubility; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D014867:Water; C009495:titanium dioxide; D014025:Titanium; C032159:acetonitrile