Dimensionality of nanoscale TiO2 determines the mechanism of photoinduced electron injection from a CdSe nanoparticle

Tafen, De Nyago; Long, Run; Prezhdo, Oleg V.

doi:10.1021/nl404352a

Title: Dimensionality of nanoscale TiO₂ determines the mechanism of photoinduced electron injection from a CdSe nanoparticle

Journal Article · Mon Mar 10 00:00:00 EDT 2014 · Nano Letters

DOI:https://doi.org/10.1021/nl404352a· OSTI ID:1165415

Tafen, De Nyago ^[1]; Long, Run ^[2]; Prezhdo, Oleg V. ^[3]

National Energy Technology Lab. (NETL), Albany, OR (United States); URS Corp., Albany, OR (United States)
Univ. College Dublin, Dublin (Ireland)
Univ. of Rochester, Rochester, NY (United States)

Assumptions about electron transfer (ET) mechanisms guide design of catalytic, photovoltaic, and electronic systems. We demonstrate that the mechanism of ET from a CdSe quantum dot (QD) into nanoscale TiO₂ depends on TiO₂ dimensionality. The injection into a TiO₂ QD is adiabatic due to strong donor–acceptor coupling, arising from unsaturated chemical bonds on the QD surface, and low density of acceptor states. In contrast, the injection into a TiO₂ nanobelt (NB) is nonadiabatic, because the state density is high, the donor–acceptor coupling is weak, and multiple phonons accommodate changes in the electronic energy. The CdSe adsorbant breaks symmetry of delocalized TiO₂ NB states, relaxing coupling selection rules, and generating more ET channels. Both mechanisms can give efficient ultrafast injection. Furthermore, the dependence on system properties is very different for the two mechanisms, demonstrating that the fundamental principles leading to efficient charge separation depend strongly on the type of nanoscale material.

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Research Organization:: National Energy Technology Lab. (NETL), Albany, OR (United States)

Sponsoring Organization:: USDOE Office of Fossil Energy (FE)

Grant/Contract Number:: FE0004000

OSTI ID:: 1165415

Report Number(s):: CONTR-PUB-044

Journal Information:: Nano Letters, Vol. 14, Issue 4; ISSN 1530-6984

Publisher:: American Chemical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 32 works

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Title: Dimensionality of nanoscale TiO2 determines the mechanism of photoinduced electron injection from a CdSe nanoparticle

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Title: Dimensionality of nanoscale TiO₂ determines the mechanism of photoinduced electron injection from a CdSe nanoparticle