title: Direct synthesis of hexagonal NaGdF₄ nanocrystals from a single-source precursor: upconverting NaGdF₄ :Yb³⁺ ,Tm³⁺ and its composites with TiO₂ for near-IR-driven photocatalysis.
abstract: A novel single-source precursor NaGd(TFA)4 (diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide-doped upconverting nanocrystals (NCs) that convert near-infrared radiation into shorter-wavelength UV/visible light. These NCs were then used to prepare well-characterized TiO2@NaGdF4:Yb(3+),Tm(3+) nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented.
authors.affiliation: University of Lyon1, IRCELYON, 2 Avenue A. Einstein, 69626 Villeurbanne (France), Fax: (+33) 472445399; Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China).
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Shashank
authors.initials: S
authors.lastname: Mishra
authors.forename: Gilles
authors.initials: G
authors.lastname: Ledoux
authors.forename: Erwann
authors.initials: E
authors.lastname: Jeanneau
authors.forename: Marlene
authors.initials: M
authors.lastname: Daniel
authors.forename: Jinlong
authors.initials: J
authors.lastname: Zhang
authors.forename: Stéphane
authors.initials: S
authors.lastname: Daniele
mesh_terms: D002384:Catalysis; D005459:Fluorides / Q000138:chemical synthesis* / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D007259:Infrared Rays; D053758:Nanoparticles / Q000737:chemistry*; D055668:Photochemical Processes; D013932:Thulium / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D015018:Ytterbium / Q000737:chemistry*
chemical_list: C009495:titanium dioxide; D013932:Thulium; D005682:Gadolinium; D014025:Titanium; D015018:Ytterbium; D005459:Fluorides
keywords: doping; fluorides; nanoparticles; photocatalysis; upconversion