The Formation Time of Ti-O• and Ti-O•-Ti Radicals at the n-SrTiO/Aqueous Interface during Photocatalytic Water Oxidation.
The initial step of photocatalytic water oxidation reaction at the metal oxide/aqueous interface involves intermediates formed by trapping photogenerated, valence band holes on different reactive sites of the oxide surface. In SrTiO these one-electron intermediates are radicals located in Ti-O• (oxy...
| Published in: | Journal of the American Chemical Society Vol. 139; no. 30; pp. 1830 - 1842 |
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| Main Authors: | , , , , , |
| Format: | Article |
| Published: |
American Chemical Society
8/2/2017
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| Subjects: | |
| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=128663430&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 128663430 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 8/2/2017 vid: 139 iid: 30 pid: 997 pub: American Chemical Society artinfo: ui: 128663430 10.1021/jacs.6b09550 ppf: 1830 ppct: 12 formats: tig: atl: The Formation Time of Ti-O• and Ti-O•-Ti Radicals at the n-SrTiO/Aqueous Interface during Photocatalytic Water Oxidation. aug: au: Chen, Xihan Choing, Stephanie N. Aschaffenburg, Daniel J. Pemmaraju, C. D. Prendergast, David Cuk, Tanja affil: Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States su: Photocatalysis Radicals Energy bands Photocatalysts Oxidation sug: subj: Photocatalysis Radicals Energy bands Photocatalysts Oxidation ab: The initial step of photocatalytic water oxidation reaction at the metal oxide/aqueous interface involves intermediates formed by trapping photogenerated, valence band holes on different reactive sites of the oxide surface. In SrTiO these one-electron intermediates are radicals located in Ti-O• (oxyl) and Ti-O•-Ti (bridge) groups arranged perpendicular and parallel to the surface respectively, and form electronic states in the band gap of SrTiO. Using an ultrafast sub band gap probe of 400 nm and white light, we excited transitions between these radical states and the conduction band. By measuring the time evolution of surface reflectivity following the pump pulse of 266 nm light, we determined an initial radical formation time of 1.3 ± 0.2 ps, which is identical to the time to populate the surface with titanium oxyl (Ti-O•) radicals. The oxyl was separately observed by a subsurface vibration near 800 cm from Ti-O located in the plane right below Ti-O•. Second, a polarized transition optical dipole allows us to assign the 1.3 ps time constant to the production of both O-site radicals. After a 4.5 ps delay, another distinct surface species forms with a time constant of 36 ± 10 ps with a yet undetermined structure. As would be expected, the radicals' decay, specifically probed by the oxyl's subsurface vibration, parallels that of the photocurrent. Our results led us to propose a nonadiabatic kinetic mechanism for generating radicals of the type Ti-O• and Ti-O•-Ti from valence band holes based on their solvation at aqueous interfaces. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2017 holdings: @attributes: islocal: N |
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