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More than protection : The function of TiO2interlayers in hematite functionalized Si photoanodes

Kawde, Anurag LU ; Annamalai, Alagappan ; Sellstedt, Anita ; Uhlig, Jens LU ; Wågberg, Thomas ; Glatzel, Pieter and Messinger, Johannes (2020) In Physical Chemistry Chemical Physics 22(48). p.28459-28467
Abstract

Worldwide significant efforts are ongoing to develop devices that store solar energy as fuels. In one such approach, solar energy is absorbed by semiconductors and utilized directly by catalysts at their surfaces to split water into H2 and O2. To protect the semiconductors in these photo-electrochemical cells (PEC) from corrosion, frequently thin TiO2 interlayers are applied. Employing a well-performing photoanode comprised of 1-D n-Si microwires (MWs) covered with a mesoporous (mp) TiO2 interlayer fabricated by solution processing and functionalized with α-Fe2O3 nanorods, we studied here the function of this TiO2 interlayer by high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy,... (More)

Worldwide significant efforts are ongoing to develop devices that store solar energy as fuels. In one such approach, solar energy is absorbed by semiconductors and utilized directly by catalysts at their surfaces to split water into H2 and O2. To protect the semiconductors in these photo-electrochemical cells (PEC) from corrosion, frequently thin TiO2 interlayers are applied. Employing a well-performing photoanode comprised of 1-D n-Si microwires (MWs) covered with a mesoporous (mp) TiO2 interlayer fabricated by solution processing and functionalized with α-Fe2O3 nanorods, we studied here the function of this TiO2 interlayer by high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy, along with X-ray emission spectroscopy (XES) and standard characterization techniques. Our data reveal that the TiO2 interlayer not only protects the n-Si MW surface from corrosion, but that it also acts as a template for the hydrothermal growth of α-Fe2O3 nanorods and improves the photocatalytic efficiency. We show that the latter effect correlates with the presence of stable oxygen vacancies at the interface between mp-TiO2 and α-Fe2O3, which act as electron traps and thereby substantially reduce the charge recombination rate at the hematite surface.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
22
issue
48
pages
9 pages
publisher
Royal Society of Chemistry
external identifiers
  • scopus:85099001289
  • pmid:33295360
ISSN
1463-9076
DOI
10.1039/d0cp04280c
language
English
LU publication?
yes
id
f274ac58-1d55-4066-9896-2b2fb14a24ae
date added to LUP
2021-01-21 12:56:26
date last changed
2024-05-17 03:34:27
@article{f274ac58-1d55-4066-9896-2b2fb14a24ae,
  abstract     = {{<p>Worldwide significant efforts are ongoing to develop devices that store solar energy as fuels. In one such approach, solar energy is absorbed by semiconductors and utilized directly by catalysts at their surfaces to split water into H2 and O2. To protect the semiconductors in these photo-electrochemical cells (PEC) from corrosion, frequently thin TiO2 interlayers are applied. Employing a well-performing photoanode comprised of 1-D n-Si microwires (MWs) covered with a mesoporous (mp) TiO2 interlayer fabricated by solution processing and functionalized with α-Fe2O3 nanorods, we studied here the function of this TiO2 interlayer by high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy, along with X-ray emission spectroscopy (XES) and standard characterization techniques. Our data reveal that the TiO2 interlayer not only protects the n-Si MW surface from corrosion, but that it also acts as a template for the hydrothermal growth of α-Fe2O3 nanorods and improves the photocatalytic efficiency. We show that the latter effect correlates with the presence of stable oxygen vacancies at the interface between mp-TiO2 and α-Fe2O3, which act as electron traps and thereby substantially reduce the charge recombination rate at the hematite surface.</p>}},
  author       = {{Kawde, Anurag and Annamalai, Alagappan and Sellstedt, Anita and Uhlig, Jens and Wågberg, Thomas and Glatzel, Pieter and Messinger, Johannes}},
  issn         = {{1463-9076}},
  language     = {{eng}},
  number       = {{48}},
  pages        = {{28459--28467}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Physical Chemistry Chemical Physics}},
  title        = {{More than protection : The function of TiO<sub>2</sub>interlayers in hematite functionalized Si photoanodes}},
  url          = {{http://dx.doi.org/10.1039/d0cp04280c}},
  doi          = {{10.1039/d0cp04280c}},
  volume       = {{22}},
  year         = {{2020}},
}