Strong Potential Gradients and Electron Confinement in ZnO Nanoparticle Films: Implications for Charge-Carrier Transport and Photocatalysis

Zinc oxide (ZnO) nanomaterials are promising components for chemical and biological sensors and photocatalytic conversion and operate as electron collectors in photovoltaic technologies. Many of these applications involve nanostructures in contact with liquids or exposed to ambient atmosphere. Under...

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Bibliographic Details
Published in:ACS applied nano materials 2021-11, Vol.4 (11), p.12213-12221
Main Authors: Mahl, Johannes, Gessner, Oliver, Barth, Johannes V, Feulner, Peter, Neppl, Stefan
Format: Article
Language:English
Subjects:
band bending
electron confinement
MATERIALS SCIENCE
nanostructures
photoemission spectroscopy
surface metallization
zinc oxide
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Summary:Zinc oxide (ZnO) nanomaterials are promising components for chemical and biological sensors and photocatalytic conversion and operate as electron collectors in photovoltaic technologies. Many of these applications involve nanostructures in contact with liquids or exposed to ambient atmosphere. Under these conditions, single-crystal ZnO surfaces are known to form narrow electron accumulation layers with few nanometer spatial penetration into the bulk. A key question is to what extent such pronounced surface potential gradients can develop in the nanophases of ZnO, where they would dominate the catalytic activity by modulating charge-carrier mobility and lifetimes. Here, we follow the temperature-dependent surface electronic structure of nanoporous ZnO with photoemission spectroscopy to reveal a sizable, spatially averaged downward band bending for the hydroxylated state and a conservative upper bound of
ISSN:2574-0970
2574-0970
DOI:10.1021/acsanm.1c02730