title: Visible light water oxidation using a co-catalyst loaded anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) compound.
abstract: The photocatalytic activity of anatase-structured Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) (x = 0.25, y = 0.02; NbN-25) was examined for water oxidation under UV and visible light irradiation. The semiconductor was prepared by sol-gel processing followed by nitridation in flowing ammonia and exhibits an indirect optical gap of 2.2 eV. Ti(1-(5x/4))Nb(x)O(2-y-δ)N(y) was loaded with RuO2 by an impregnation technique, and optimized conditions reveal that 1 wt % RuO2 generates 16 μmol O2 from water with concomitant IO3(-) reduction after 3 h of illumination under simulated solar radiation at a flux of 600 mW/cm(2) illumination, which corresponds to 6-sun AM1.5G illumination (compared to no detectible O2 without the RuO2 cocatalyst). A series of cut-on filters shows that the catalyst-loaded semiconductor evolves O2 for λ ≤ 515 nm, and a gas-phase mass spectrometry isotope labeling experiment shows that irradiating an iodate solution in H2(18)O in the presence of 1 wt % RuO2 loaded on NbN-25 gives rise to catalytic water oxidation: both (36)O2 and (34)O2 are observed. It is unclear whether (16)O arises from IO3(-) or surface reconstruction on the photocatalyst, but ICP-AES analysis of the postirradiated solution shows no dissolved metal ions.
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, Michigan 48109, United States.
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Breault
authors.forename: James J
authors.initials: JJ
authors.lastname: Brancho
authors.forename: Ping
authors.initials: P
authors.lastname: Guo
authors.forename: Bart M
authors.initials: BM
authors.lastname: Bartlett
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry*; D008027:Light; D009556:Niobium / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010316:Particle Size; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D009556:Niobium; D014867:Water; C009495:titanium dioxide; D003035:Cobalt; D014025:Titanium; D009584:Nitrogen; D010100:Oxygen