THESIS
2012
xii, 91 p. : ill. ; 30 cm
Abstract
In this study, the efficacy with which TiO
2/carbon nanomaterials composites enhance ⋅OH generation was investigated. Nano-assemblies comprising different proportions of TiO
2 and multi-walled carbon nanotubes, single-walled carbon nanotubes, or fullerol were synthesized by a low temperature hydration-dehydration process and characterized by TEM, XPS, and UV-vis. Photocatalytic performance enhancement of all the TiO
2/carbon nanomaterial composites was quantified by nitrobenzene degradation or MS2 bacteriophage inactivation under UVA irradiation. The photoreactivity of the composites with respect to nitrobenzene (NB) oxidation and MS2 bacteriophage inactivation was found higher than that of TiO
2 and the optimum composition determined, which was TiO
2 to SWCNT prepared at mass ratio of 50:1....[
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In this study, the efficacy with which TiO
2/carbon nanomaterials composites enhance ⋅OH generation was investigated. Nano-assemblies comprising different proportions of TiO
2 and multi-walled carbon nanotubes, single-walled carbon nanotubes, or fullerol were synthesized by a low temperature hydration-dehydration process and characterized by TEM, XPS, and UV-vis. Photocatalytic performance enhancement of all the TiO
2/carbon nanomaterial composites was quantified by nitrobenzene degradation or MS2 bacteriophage inactivation under UVA irradiation. The photoreactivity of the composites with respect to nitrobenzene (NB) oxidation and MS2 bacteriophage inactivation was found higher than that of TiO
2 and the optimum composition determined, which was TiO
2 to SWCNT prepared at mass ratio of 50:1.
The role of single-walled carbon nanotubes (SWCNTs) and fullerol in enhancing photocatalytic activity of nanostructured composites was elucidated in this study. Probing tests employing hydroxyl radical scavengers showed that the surface-bound ⋅OH generation of SWCNTs was more than that of TiO
2. Using the hole scavenger, sodium oxalate at different concentration levels indicated that more photogenerated holes on TiO
2/SWCNT composites than TiO
2 along. The addition of Fe
3+, an electron scavenger to both TiO
2/SWCNT and TiO
2/fullerol systems revealed the similar function of SWCNT and fullerol as an electron scavenger. The results indicated that SWCNT and fullerol altered the pathway of electrons photoexicited from TiO
2, suggesting electron capture by SWCNT and fullerol to retard TiO
2’s electron-hole recombination, consistent with the increased generation of H
2O
2 by the TiO
2/SWCNT or TiO
2/fullerol composites within the testing period.
In spite of the similarities of the roles SWCNT and fullerol played in TiO
2 photocatalysis enhancement, their enhancement over TiO
2 alone and durability varied because of their different structural, chemical and electrical properties. SWCNT proved to have a more significant enhancement over TiO
2 than fullerol. Additionally, due to the longer life span and better chemical stability, SWCNT appeared to be the preferable photocatalyst support.
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