title: Chemically directed assembly of photoactive metal oxide nanoparticle heterojunctions via the copper-catalyzed azide-alkyne cycloaddition "click" reaction.
abstract: Metal oxides play a key role in many emerging applications in renewable energy, such as dye-sensitized solar cells and photocatalysts. Because the separation of charge can often be facilitated at junctions between different materials, there is great interest in the formation of heterojunctions between metal oxides. Here, we demonstrate use of the copper-catalyzed azide-alkyne cycloaddition reaction, widely referred to as "click" chemistry, to chemically assemble photoactive heterojunctions between metal oxide nanoparticles, using WO(3) and TiO(2) as a model system. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy verify the nature and selectivity of the chemical linkages, while scanning electron microscopy reveals that the TiO(2) nanoparticles form a high-density, conformal coating on the larger WO(3) nanoparticles. Time-resolved surface photoresponse measurements show that the resulting dyadic structures support photoactivated charge transfer, while measurements of the photocatalytic degradation of methylene blue show that chemical grafting of TiO(2) nanoparticles to WO(3) increases the photocatalytic activity compared with the bare WO(3) film.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
authors.forename: Allison C
authors.initials: AC
authors.lastname: Cardiel
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Benson
authors.forename: Lee M
authors.initials: LM
authors.lastname: Bishop
authors.forename: Kacie M
authors.initials: KM
authors.lastname: Louis
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Yeager
authors.forename: Yizheng
authors.initials: Y
authors.lastname: Tan
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hamers
mesh_terms: D000480:Alkynes / Q000737:chemistry; D001386:Azides / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry* / Q000528:radiation effects; D003460:Crystallization / Q000379:methods*; D008027:Light; D046911:Macromolecular Substances / Q000737:chemistry / Q000528:radiation effects; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D008968:Molecular Conformation / Q000528:radiation effects; D010087:Oxides / Q000737:chemistry* / Q000528:radiation effects; D010316:Particle Size; D012666:Semiconductors; D013499:Surface Properties / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014414:Tungsten / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D000480:Alkynes; D001386:Azides; D046911:Macromolecular Substances; D010087:Oxides; C009495:titanium dioxide; D003300:Copper; C511604:tungsten oxide; D014025:Titanium; D014414:Tungsten