Developing efficient photocatalysts for high-performance decomposition of perfluorooctanoic acid

Liu, Xiaoqing

Developing efficient photocatalysts for high-performance decomposition of perfluorooctanoic acid

Liu, Xiaoqing

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Publication Type:: Thesis
Issue Date:: 2022

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Field	Value	Language
dc.contributor.author	Liu, Xiaoqing
dc.date.accessioned	2022-11-03T03:48:15Z
dc.date.available	2022-11-03T03:48:15Z
dc.date.issued	2022
dc.identifier.uri	http://hdl.handle.net/10453/163178
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	Perfluorochemicals (PFCs) are a set of chemicals containing C-F bonds, which are concerned due to their persistent and toxicological properties. Perfluorooctanoic acid (PFOA, C7F15COOH) is one of the most widely used PFCs. Photocatalytic approaches appear to be an effective way for the removal of PFCs. We first used metal-organic frameworks (MOFs) derived In2O3 for photocatalytic degradation of PFOA under UV light irradiation. The results show that PFOA was completely decomposed in 3 h. MOFs-derived In2O3 was super-hydrophilic with a contact angle of ~20º, which facilitated the tight coordination between PFOA and In2O3. Lower calcination temperatures enable higher oxygen vacancy concentrations and larger specific surface area (SSA) of In2O3. In2O3 prepared at 300 ºC (In2O3-300) and 400 ºC (In2O3-400) demonstrated better catalytic performance, and PFOA (10 mg L‒1) could be completely removed within 4 h, with a defluorination ratio of 39% over In2O3-400 in 8h. Fe3+ only slightly increased the defluorination ratio of PFOA over In2O3-400 to 43%. A much higher defluorination ratio of ~60% was obtained in In2O3-600 system after the addition of Fe3+, than the defluorination ratio of ~20% over In2O3-600. Combined with a series of characterizations, we speculated that Fe3+ participated in the coordination between PFOA and In2O3-600, thus promoting the defluorination of PFOA. The BiOX/TiO2 heterojunctions demonstrated significantly enhanced efficiency for photocatalytic decomposition of perfluorooctanoic acid (PFOA) compared with BiOX or TiO2. PFOA (10 mg L‒1) was completely degraded by BiOCl/TiO2 in 8h with a high defluorination ratio of 82 %. The charge transfer and photo-induced electron hole separation were facilitated by the p-n heterojunctions between BiOX and TiO2 and the inner electric fields (IEF) in BiOX. XRD and TEM characterizations indicated that TiO2 combined with BiOX along the [110] facet, which facilitated photo-induced electron transfer in the [001] direction, thus benefiting PFOA decomposition. Single bismuth (Bi) atoms decorated TiO2 catalyst (N-Bi/TiO2) was synthesized by a green and simple UV irradiation method using Bi(NO3)3 as the precursor. When BiCl3 was used as the Bi precursor, BiOCl nanocluster were formed on the surface of TiO2 (denoted as Cl-Bi/TiO2). Both N-Bi/TiO2 and Cl-Bi/TiO2 demonstrated excellent performance for the defluorination of PFOA. In-situ DRIFTS spectra demonstrated that the Bi single atoms in N-Bi/TiO2 induced the ionization of C-F bond of PFOA, leading to the deep defluorination of PFOA. Our findings provide approaches for manipulating the photocatalytic activities of In2O3 and TiO2-based composites for the high-performance decomposition of PFOA.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/163178/2/02whole.pdf
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Developing efficient photocatalysts for high-performance decomposition of perfluorooctanoic acid	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Perfluorochemicals (PFCs) are a set of chemicals containing C-F bonds, which are concerned due to their persistent and toxicological properties. Perfluorooctanoic acid (PFOA, C7F15COOH) is one of the most widely used PFCs. Photocatalytic approaches appear to be an effective way for the removal of PFCs. We first used metal-organic frameworks (MOFs) derived In2O3 for photocatalytic degradation of PFOA under UV light irradiation. The results show that PFOA was completely decomposed in 3 h. MOFs-derived In2O3 was super-hydrophilic with a contact angle of ~20º, which facilitated the tight coordination between PFOA and In2O3. Lower calcination temperatures enable higher oxygen vacancy concentrations and larger specific surface area (SSA) of In2O3. In2O3 prepared at 300 ºC (In2O3-300) and 400 ºC (In2O3-400) demonstrated better catalytic performance, and PFOA (10 mg L‒1) could be completely removed within 4 h, with a defluorination ratio of 39% over In2O3-400 in 8h. Fe3+ only slightly increased the defluorination ratio of PFOA over In2O3-400 to 43%. A much higher defluorination ratio of ~60% was obtained in In2O3-600 system after the addition of Fe3+, than the defluorination ratio of ~20% over In2O3-600. Combined with a series of characterizations, we speculated that Fe3+ participated in the coordination between PFOA and In2O3-600, thus promoting the defluorination of PFOA. The BiOX/TiO2 heterojunctions demonstrated significantly enhanced efficiency for photocatalytic decomposition of perfluorooctanoic acid (PFOA) compared with BiOX or TiO2. PFOA (10 mg L‒1) was completely degraded by BiOCl/TiO2 in 8h with a high defluorination ratio of 82 %. The charge transfer and photo-induced electron hole separation were facilitated by the p-n heterojunctions between BiOX and TiO2 and the inner electric fields (IEF) in BiOX. XRD and TEM characterizations indicated that TiO2 combined with BiOX along the [110] facet, which facilitated photo-induced electron transfer in the [001] direction, thus benefiting PFOA decomposition. Single bismuth (Bi) atoms decorated TiO2 catalyst (N-Bi/TiO2) was synthesized by a green and simple UV irradiation method using Bi(NO3)3 as the precursor. When BiCl3 was used as the Bi precursor, BiOCl nanocluster were formed on the surface of TiO2 (denoted as Cl-Bi/TiO2). Both N-Bi/TiO2 and Cl-Bi/TiO2 demonstrated excellent performance for the defluorination of PFOA. In-situ DRIFTS spectra demonstrated that the Bi single atoms in N-Bi/TiO2 induced the ionization of C-F bond of PFOA, leading to the deep defluorination of PFOA. Our findings provide approaches for manipulating the photocatalytic activities of In2O3 and TiO2-based composites for the high-performance decomposition of PFOA.

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