title: Photocatalytic activity of titanium dioxide modified by silver nanoparticles.
abstract: Photocatalytic activity of Ag/TiO(2) composites obtained by photoreduction treatment (PRT) was investigated. The composite materials, containing various ratio of silver nanoparticles (0.6-3.7 wt %) were obtained by depositing silver on the Evonic-Degussa P25 titania surface. Selected samples whose color varied between light rose and purple brown were examined by SEM, TEM, XPS, DRS, and BET techniques. Flat band potential was determined using Roy method. TEM analysis showed spherically shaped silver nanoparticles of the diameter 4-12 nm. The XPS measurements revealed that silver particles were obtained mainly in metallic form. DRS spectra and photovoltage measurements showed that silver nanoparticles modified the P25 spectral properties but they changed neither the band gap nor the location of flat band potential. The photocatalytic activity of Ag/P25 composite was compared to the photocatalytic activity of pure P25 in the photooxidation reaction of an important potable water contaminant humic acid (HA) and two model compounds, oxalic acid (OxA) and formic acid (FA). The photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that a small amount of silver nanoparticles deposited on the titania surface triggers the increase in photocatalytic activity; this increase depends, however, on the decomposed substance.
authors.affiliation: Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30-239 Krakow, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Wodka
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Bielańska
authors.forename: Robert P
authors.initials: RP
authors.lastname: Socha
authors.forename: Magdalena
authors.initials: M
authors.lastname: Elzbieciak-Wodka
authors.forename: Jacek
authors.initials: J
authors.lastname: Gurgul
authors.forename: Paweł
authors.initials: P
authors.lastname: Nowak
authors.forename: Piotr
authors.initials: P
authors.lastname: Warszyński
authors.forename: Izumi
authors.initials: I
authors.lastname: Kumakiri
mesh_terms: D002384:Catalysis; D006812:Humic Substances; D053768:Metal Nanoparticles / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D055668:Photochemical Processes; D012834:Silver / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D006812:Humic Substances; C009495:titanium dioxide; D012834:Silver; D014025:Titanium