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Title: Strong O 2p–Fe 3d Hybridization Observed in Solution-Grown Hematite Films by Soft X-ray Spectroscopies

Abstract

Photoelectrochemical (PEC) water splitting holds the potential as a direct route for solar energy conversation and storage. The performance of a PEC device is strongly influenced by the electronic properties of the photonanode surface. It has been shown that the synthesis methods can have a profound impact on the electronic properties and PEC performance of various photoelectrode materials such as hematite. Soft X-ray spectroscopic techniques, including O K-edge XAS and Fe L-edge XAS/XES, have been employed to investigate how the synthesis methods impact the electronic structure of resulting hematite materials. It is found that the hematite samples via solution regrowth methods show dramatically increased 3d-4sp band ratios in O K-edge XAS spectra and decreased relative elastic peak intensities in Fe L-edge RIXS spectra compared with samples synthesized via ALD or solution grown. The difference observed in O-K and Fe-L spectra indicated that solution regrowth strategy alters the O 2p-Fe 3d hybridization and hence the electronic structure of the hematite films, which proves to be beneficial for PEC performance of the hematite photoanode. Our findings provided new insights and potentially useful strategies for enhancing the PEC performance of photoanode materials.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [1];  [1];  [2];  [2];  [2]; ORCiD logo [2]; ORCiD logo [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  2. Boston College, Chestnut Hill, MA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); Univ. of California, Santa Cruz, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1530329
Grant/Contract Number:  
[AC02-05CH11231]
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
[ Journal Volume: 122; Journal Issue: 2]; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Ye, Yifan, Thorne, James E., Wu, Cheng Hao, Liu, Yi-Sheng, Du, Chun, Jang, Ji-Wook, Liu, Erik, Wang, Dunwei, and Guo, Jinghua. Strong O 2p–Fe 3d Hybridization Observed in Solution-Grown Hematite Films by Soft X-ray Spectroscopies. United States: N. p., 2017. Web. doi:10.1021/acs.jpcb.7b06989.
Ye, Yifan, Thorne, James E., Wu, Cheng Hao, Liu, Yi-Sheng, Du, Chun, Jang, Ji-Wook, Liu, Erik, Wang, Dunwei, & Guo, Jinghua. Strong O 2p–Fe 3d Hybridization Observed in Solution-Grown Hematite Films by Soft X-ray Spectroscopies. United States. doi:10.1021/acs.jpcb.7b06989.
Ye, Yifan, Thorne, James E., Wu, Cheng Hao, Liu, Yi-Sheng, Du, Chun, Jang, Ji-Wook, Liu, Erik, Wang, Dunwei, and Guo, Jinghua. Wed . "Strong O 2p–Fe 3d Hybridization Observed in Solution-Grown Hematite Films by Soft X-ray Spectroscopies". United States. doi:10.1021/acs.jpcb.7b06989. https://www.osti.gov/servlets/purl/1530329.
@article{osti_1530329,
title = {Strong O 2p–Fe 3d Hybridization Observed in Solution-Grown Hematite Films by Soft X-ray Spectroscopies},
author = {Ye, Yifan and Thorne, James E. and Wu, Cheng Hao and Liu, Yi-Sheng and Du, Chun and Jang, Ji-Wook and Liu, Erik and Wang, Dunwei and Guo, Jinghua},
abstractNote = {Photoelectrochemical (PEC) water splitting holds the potential as a direct route for solar energy conversation and storage. The performance of a PEC device is strongly influenced by the electronic properties of the photonanode surface. It has been shown that the synthesis methods can have a profound impact on the electronic properties and PEC performance of various photoelectrode materials such as hematite. Soft X-ray spectroscopic techniques, including O K-edge XAS and Fe L-edge XAS/XES, have been employed to investigate how the synthesis methods impact the electronic structure of resulting hematite materials. It is found that the hematite samples via solution regrowth methods show dramatically increased 3d-4sp band ratios in O K-edge XAS spectra and decreased relative elastic peak intensities in Fe L-edge RIXS spectra compared with samples synthesized via ALD or solution grown. The difference observed in O-K and Fe-L spectra indicated that solution regrowth strategy alters the O 2p-Fe 3d hybridization and hence the electronic structure of the hematite films, which proves to be beneficial for PEC performance of the hematite photoanode. Our findings provided new insights and potentially useful strategies for enhancing the PEC performance of photoanode materials.},
doi = {10.1021/acs.jpcb.7b06989},
journal = {Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry},
number = [2],
volume = [122],
place = {United States},
year = {2017},
month = {11}
}

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Figures / Tables:

Figure 1 Figure 1: O K-edge XAS signals of Hematite films synthesized by different methods, the peak decomposition has also indicated in the figure. The experimental data is shown with the open circles and the fitted results are shown with the solid line. The substrate signals are included to fit the TFYmore » spectra and displayed by dash lines.« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.