Photocatalytic reactivities of Nafion-Coated TiO2 for the degradation of charged organic compounds under UV or visible light
SCIE
SCOPUS
- Title
- Photocatalytic reactivities of Nafion-Coated TiO2 for the degradation of charged organic compounds under UV or visible light
- Authors
- Park, H; Choi, W
- Date Issued
- 2005-06-16
- Publisher
- AMER CHEMICAL SOC
- Abstract
- Nafion (perfluorinated polymer with sulfonate groups)-coated TiO2 particles (Nf/TiO2) were prepared and their reactivities for the photocatalytic degradation (PCD) of charged organic substrates were investigated. The presence of Nafion adlayers drastically changed the positive TiO2 surface charge to a negative one over the entire pH range and significantly influenced the PCD kinetics and mechanisms. The UV-induced PCD of tetramethylammonium (TMA; cationic substrate) was greatly enhanced in the presence of Nafion adlayers on TiO2 because the ion-exchange sites within the Nafion can hold cationic substrates. On the other hand, despite the unfavorable electrostatic interaction between the Nf/TiO2 and anionic substrates, the PCD of dichloroacetate (DCA) and acid orange 7 (AO7) with Nf/TiO2 was not significantly inhibited. The visible-light-sensitized degradation of dyes was enhanced with Nf/TiO2 not only for cationic dyes (methylene blue (MB) and rhodamine B (RhB)) whose uptake on Nf/TiO2 is enhanced, but also for an anionic dye (A07) that is less adsorbed on Nf/TiO2. The unexpected behavior in A07 degradation seems to be related to the role of the Nafion layer in retarding the charge recombination. These observations indicate that Nf/TiO2 can enhance the PCD reactivity for cationic substrates without sacrificing the PCD reactivity for anionic substrates. In addition, it was found that the sensitized degradation of RhB followed a different path when the surface of TiO2 was coated with Nafion. The N-de-ethylation of RhB that leads to the generation of rhodamine-110 was a prevailing path with Nf/TiO2, whereas the cleavage of the chromophoric ring structure was dominant with pure TiO2. The effects of Nafion adlayers on the photoinduced electron transfer and PCD kinetics and mechanisms are discussed.
- Keywords
- TITANIUM-DIOXIDE; METHYLENE-BLUE; PHOTOSENSITIZED DEGRADATION; SEMICONDUCTOR SURFACES; PLATINUM DEPOSITS; RHODAMINE-B; AZO-DYE; IRRADIATION; KINETICS; OXIDATION
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/24547
- DOI
- 10.1021/JP051222S
- ISSN
- 1520-6106
- Article Type
- Article
- Citation
- JOURNAL OF PHYSICAL CHEMISTRY B, vol. 109, no. 23, page. 11667 - 11674, 2005-06-16
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