Revealing hole trapping in zinc oxide nanoparticles by time-resolved X-ray spectroscopy

Nanostructures of transition metal oxides, such as zinc oxide, have attracted considerable interest for solar-energy conversion and photocatalysis. Both applications are sensitive to the transport and trapping of photoexcited charge carriers. The probing of electron trapping has recently become poss...

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Bibliographic Details
Published in:Nature communications Vol. 9; no. 1; pp. 478 - 9
Main Authors: Penfold, Thomas J., Szlachetko, Jakub, Santomauro, Fabio G., Britz, Alexander, Gawelda, Wojciech, Doumy, Gilles, March, Anne Marie, Southworth, Stephen H., Rittmann, Jochen, Abela, Rafael, Chergui, Majed, Milne, Christopher J.
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 02.02.2018
Nature Publishing Group
Nature Portfolio
Subjects:
639/624/400/1106
639/638/298/398
639/925/357/354
Absorption spectroscopy
Current carriers
Energy conversion
Hole traps
Humanities and Social Sciences
multidisciplinary
Nanoparticles
NANOSCIENCE AND NANOTECHNOLOGY
Nanotechnology devices
Optical materials
Oxides
Photoexcitation
Science
Science (multidisciplinary)
Solar energy
Spectrum analysis
Transition metal oxides
Trapping
Vacancies
X-ray absorption spectroscopy
X-ray spectroscopy
X-rays
Zinc oxide
Zinc oxides
ISSN:2041-1723, 2041-1723
Online Access:Get full text
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Summary:Nanostructures of transition metal oxides, such as zinc oxide, have attracted considerable interest for solar-energy conversion and photocatalysis. Both applications are sensitive to the transport and trapping of photoexcited charge carriers. The probing of electron trapping has recently become possible using time-resolved element-sensitive methods, such as X-ray spectroscopy. However, valence-band-trapped holes have so far escaped observation. Herein we use X-ray absorption spectroscopy combined with a dispersive X-ray emission spectrometer to probe the charge carrier relaxation and trapping processes in zinc oxide nanoparticles after above band-gap photoexcitation. Our results, supported by simulations, demonstrate that within 80 ps, photoexcited holes are trapped at singly charged oxygen vacancies, which causes an outward displacement by ~15% of the four surrounding zinc atoms away from the doubly charged vacancy. This identification of the hole traps provides insight for future developments of transition metal oxide-based nanodevices. Metal-oxide nanostructures are used in a range of light-driven applications, yet the fundamentals behind their properties are poorly understood. Here the authors probe photoexcited zinc oxide nanoparticles using time-resolved X-ray spectroscopy, identifying photocatalytically-active hole traps as oxygen vacancies in the lattice.
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German Research Foundation (DFG)
National Science Centre, Poland (NCN)
European Research Council (ERC)
AC02-06CH11357; 2015/18/E/ST3/00444; 2016/ 22/E/ST4/00543
Swiss National Science Foundation (SNSF)
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-018-02870-4