title: Influence of visible-light irradiation on physicochemical and photocatalytic properties of nitrogen-doped three-dimensional (3D) titanium dioxide.
abstract: We report highly active visible-light driven nitrogen-doped three-dimensional polycrystalline anatase TiO2 photocatalysts (N-3D TiO2) for environmental and biomedical applications. N-3D TiO2 is synthesized at a low temperature (<90°C) without thermal treatment via a modified hydrothermal process (HP) and ultrasound irradiation (UI). The N-3D TiO2 is additionally irradiated with visible-light to improve the hydroxylation of its surface. Under visible-light irradiation, the photocatalytic activity of visible-light irradiated N-3D TiO2 (*N-3D TiO2; [k]=1.435 h(-1)) is 26.1 times higher than that of 3D TiO2 ([k]=0.055 h(-1)). The *N-3D TiO2 is highly recyclable and retained 91.8% of the initial decolorization rate after fifteen cycles. Interestingly, the *N-3D TiO2 shows very strong antibacterial properties against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) after exposure to visible-light for 3h. The antibacterial properties of *N-3D TiO2 are more effective than those of TiO2, 3D TiO2, and N-3D TiO2. More than 91.3% of the E. coli is sterilized after ten cycles. There are a large increase in the photocatalytic and antibacterial activity of *N-3D TiO2 relative to that of N-3D TiO2 owing to the hydroxylation of the N-3D TiO2 surface as a result of the visible-light irradiation. These results indicate that *N-3D TiO2 might have utility in several promising applications such as highly efficient water/air treatment, inactivation of pathogenic microorganisms, and solar-energy conversion.
authors.affiliation: Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333, Republic of Korea. biolhu@hanmail.net
authors.forename: Hyun Uk
authors.initials: HU
authors.lastname: Lee
authors.forename: Soon Chang
authors.initials: SC
authors.lastname: Lee
authors.forename: Saehae
authors.initials: S
authors.lastname: Choi
authors.forename: Byoungchul
authors.initials: B
authors.lastname: Son
authors.forename: Hyeran
authors.initials: H
authors.lastname: Kim
authors.forename: Sang Moon
authors.initials: SM
authors.lastname: Lee
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jouhahn
authors.initials: J
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects; D002384:Catalysis; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism; D006900:Hydroxylation; D008027:Light; D009584:Nitrogen / Q000737:chemistry*; D055668:Photochemical Processes; D013211:Staphylococcus aureus / Q000187:drug effects / Q000378:metabolism; D013472:Sunlight; D013696:Temperature; D014025:Titanium / Q000737:chemistry / Q000494:pharmacology / Q000528:radiation effects*
chemical_list: D000900:Anti-Bacterial Agents; C009495:titanium dioxide; D014025:Titanium; D009584:Nitrogen