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Chen Y, Bhati M, Walls BW, Wang B, Wong MS, Senftle TP. Mechanistic Insight into the Photo-Oxidation of Perfluorocarboxylic Acid over Boron Nitride. Environ Sci Technol 2022; 56:8942-8952. [PMID: 35617117 DOI: 10.1021/acs.est.2c01637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hexagonal boron nitride (hBN) can photocatalytically oxidize and degrade perfluorocarboxylic acids (PFCA), a common member of the per/polyfluoroalkyl substance (PFAS) family of water contaminants. However, the reaction mechanism governing PFCA activation on hBN is not yet understood. Here, we apply electronic grand canonical density functional theory (GC-DFT) to assess the thermodynamic and kinetic favorability of PFCA photo-oxidative activation on hBN: CnF2n+1COO- + h+ → CnF2n+1· + CO2. The oxidation of all PFCA chains is exothermic under illumination with a moderate barrier. However, the longer-chain PFCAs are degraded more effectively because they adsorb on the surface more strongly as a result of increased van der Waals interactions with the hBN surface. The ability of hBN to act as a photocatalyst is unexpected because of its wide band gap. Therefore, we apply both theoretical and experimental analyses to examine possible defects on hBN that could account for its activity. We find that a nitrogen-boron substitutional defect (NB), which generates a mid-gap state, can enhance UVC (ultraviolet C) absorption and PFCA oxidation. This work provides insight into the PFCA oxidation mechanism and reveals engineering strategies to design better photocatalysts for PFCA degradation.
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Affiliation(s)
- Yu Chen
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Houston, Texas 77005, United States
| | - Manav Bhati
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Houston, Texas 77005, United States
| | - Benjamin W Walls
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
| | - Bo Wang
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Houston, Texas 77005, United States
| | - Michael S Wong
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Houston, Texas 77005, United States
- Department of Environmental Engineering, Rice University, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, United States
| | - Thomas P Senftle
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, Texas 77005-1892, United States
- Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, Houston, Texas 77005, United States
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Ahn CH, Deshpande NG, Lee HS, Cho HK. Energy Transfer-Induced Photoelectrochemical Improvement from Porous Zeolitic Imidazolate Framework-Decorated BiVO 4 Photoelectrodes. Small Methods 2021; 5:e2000753. [PMID: 34927880 DOI: 10.1002/smtd.202000753] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/08/2020] [Indexed: 06/14/2023]
Abstract
BiVO4 , which is a representative photoanode material for photoelectrochemical water splitting, intrinsically restricts high conversion efficiency, owing to faster recombination, low electron mobility, and short electron diffusion length. While the photocurrent density of typical BiVO4 corresponds to only 21.3% of the maximum photocurrent density (4.68 mA cm-2 ), decoration of the BiVO4 photoanode with zeolitic imidazolate framework-67 (ZIF-67) exhibits a synergetic effect to raise the overall photocatalytic ability at the BiVO4 surface region to a higher level via the energy-transfer process from BiVO4 to ZIF-67. The hybrid ZIF-67/BiVO4 photoanode follows two convenient photoelectrochemical pathways: 1) energy-transfer-induced water oxidation reaction in ZIF-67 and 2) water oxidation reaction by direct contact between the BiVO4 surface and electrolytes. Compared to the moderate photocurrent density (≈1 mA cm-2 ) of single-layer BiVO4 , the proposed ZIF-67/BiVO4 photoanodes show a remarkably high photocurrent (2.25 mA cm-2 ) with high stability, despite the lack of hole scavengers in the electrolyte. Furthermore, the absorbed photon-to-current efficiency of the ZIF-67/BiVO4 photoanode is ≈2.5 times greater than that of BiVO4 . This work proposes a promising solution for efficient water oxidation that overcomes the intrinsic material limitations of BiVO4 photoelectrodes by using energy transfer-induced photon recycling and the decoration of porous ZIFs.
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Affiliation(s)
- Cheol Hyoun Ahn
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
- Research Center for Advanced Materials Technology, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Nishad G Deshpande
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
- Research Center for Advanced Materials Technology, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
| | - Ho Seong Lee
- School of Materials Science and Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea
| | - Hyung Koun Cho
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
- Research Center for Advanced Materials Technology, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 16419, Republic of Korea
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