Photo-induced Charge Separation across the Graphene–TiO Interface Is Faster than Energy Losses: A Time-Domain ab Initio Analysis.
Graphene-TiO composites exhibit excellent potential for photovoltaic applications, provided that efficient photoinduced charge separation can be achieved at the interface. Once charges are separated, TiO acts as an electron carrier, while graphene is an excellent hole conductor. However, charge sepa...
| Publicado en: | Journal of the American Chemical Society Vol. 134; no. 34; pp. 14238 - 14249 |
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| Autores principales: | , , |
| Formato: | Artículo |
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American Chemical Society
8/29/2012
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=80073573&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 80073573 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: 8/29/2012 vid: 134 iid: 34 pid: 997 pub: American Chemical Society artinfo: ui: 80073573 10.1021/ja3063953 ppf: 14238 ppct: 11 formats: tig: atl: Photo-induced Charge Separation across the Graphene–TiO Interface Is Faster than Energy Losses: A Time-Domain ab Initio Analysis. aug: au: Run Long English, Niall J. Prezhdo, Oleg V. affil: Department of Chemistry, University of Rochester, New York 14620, United States Complex & Adaptive Systems Laboratory, School of Physics, University College Dublin, Belfield, Dublin 4, Ireland SEC Research Cluster, School of Chemical & Bioprocess Engineering, University College Dublin, Belfield, Dublin 4, Ireland su: Analytical chemistry Density functionals Surface chemistry Molecular dynamics Energy dissipation sug: subj: Analytical chemistry Density functionals Surface chemistry Molecular dynamics Energy dissipation ab: Graphene-TiO composites exhibit excellent potential for photovoltaic applications, provided that efficient photoinduced charge separation can be achieved at the interface. Once charges are separated, TiO acts as an electron carrier, while graphene is an excellent hole conductor. However, charge separation competes with energy losses that can result in rapid electron-hole annihilation inside metallic graphene. Bearing this in mind, we investigate the mechanisms and, crucially, time scales of electron transfer and energy relaxation processes. Using nonadiabatic molecular dynamics formulated within the framework of time-domain density functional theory, we establish that the photoinduced electron transfer occurs several times faster than the electron-phonon energy relaxation (i.e., charge separation is efficient in the presence of electron-phonon relaxation), thereby showing that graphene-TiO interfaces can form the basis for photovoltaic and photocatalytic devices using visible light. We identify the mechanisms for charge separation and energy losses, both of which proceed by rapid, phonon-induced nonadiabatic transitions within the manifold of the electronic states. Electron injection is ultrafast, owing to strong electronic coupling between graphene and TiO. Injection is promoted by both out-of-plane graphene motions, which modulate the graphene-TiO distance and interaction, and high-frequency bond stretching and bending vibrations, which generate large nonadiabatic coupling. Both electron injection and energy transfer, injection in particular, accelerate for photoexcited states that are delocalized between the two subsystems. The theoretical results show excellent agreement with the available experimental data [ Adv. Funct. Mater. 2009, 19, 3638]. The state-of-the-art simulation generates a detailed time-domain atomistic description of the interfacial charge separation and relaxation processes that are fundamental to a wide variety of applications, including catalysis, electrolysis, and photovoltaics. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2012 holdings: @attributes: islocal: N |
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