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Title: Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite

Abstract

Electrocatalysts improve the efficiency of light-absorbing semiconductor photoanodes driving the oxygen evolution reaction, but the precise function(s) of the electrocatalysts remains unclear. We directly measure, for the first time, the interface carrier transport properties of a prototypical visible-light-absorbing semiconductor, α-Fe 2O 3, in contact with one of the fastest known water oxidation catalysts, Ni 0.8Fe 0.2O x, by directly measuring/controlling the current and/or voltage at the Ni 0.8Fe 0.2O x catalyst layer using a second working electrode. The measurements demonstrate that the majority of photogenerated holes in α-Fe 2O 3 directly transfer to the catalyst film over a wide range of conditions and that the Ni 0.8Fe 0.2O x is oxidized by photoholes to an operating potential sufficient to drive water oxidation at rates that match the photocurrent generated by the α-Fe 2O 3. The Ni 0.8Fe 0.2O x therefore acts as both a hole-collecting contact and a catalyst for the photoelectrochemical water oxidation process. Separate measurements show that the illuminated junction photovoltage across the α-Fe 2O 3|Ni 0.8Fe 0.2O x interface is significantly decreased by the oxidation of Ni 2+ to Ni 3+ and the associated increase in the Ni 0.8Fe 0.2O x electrical conductivity. Finally, in sum, themore » results illustrate the underlying operative charge-transfer and photovoltage generation mechanisms of catalyzed photoelectrodes, thus guiding their continued improvement.« less

Authors:
 [1];  [2];  [1];  [1]; ORCiD logo [2]; ORCiD logo [1]
  1. Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, Eugene, Oregon 97403, United States
  2. Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
Publication Date:
Research Org.:
Univ. of Oregon, Eugene, OR (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
OSTI Identifier:
1375497
Alternate Identifier(s):
OSTI ID: 1421383
Grant/Contract Number:  
SC0014279
Resource Type:
Journal Article: Published Article
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Name: ACS Central Science Journal Volume: 3 Journal Issue: 9; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Qiu, Jingjing, Hajibabaei, Hamed, Nellist, Michael R., Laskowski, Forrest A. L., Hamann, Thomas W., and Boettcher, Shannon W. Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite. United States: N. p., 2017. Web. doi:10.1021/acscentsci.7b00310.
Qiu, Jingjing, Hajibabaei, Hamed, Nellist, Michael R., Laskowski, Forrest A. L., Hamann, Thomas W., & Boettcher, Shannon W. Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite. United States. https://doi.org/10.1021/acscentsci.7b00310
Qiu, Jingjing, Hajibabaei, Hamed, Nellist, Michael R., Laskowski, Forrest A. L., Hamann, Thomas W., and Boettcher, Shannon W. Thu . "Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite". United States. https://doi.org/10.1021/acscentsci.7b00310.
@article{osti_1375497,
title = {Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite},
author = {Qiu, Jingjing and Hajibabaei, Hamed and Nellist, Michael R. and Laskowski, Forrest A. L. and Hamann, Thomas W. and Boettcher, Shannon W.},
abstractNote = {Electrocatalysts improve the efficiency of light-absorbing semiconductor photoanodes driving the oxygen evolution reaction, but the precise function(s) of the electrocatalysts remains unclear. We directly measure, for the first time, the interface carrier transport properties of a prototypical visible-light-absorbing semiconductor, α-Fe2O3, in contact with one of the fastest known water oxidation catalysts, Ni0.8Fe0.2Ox, by directly measuring/controlling the current and/or voltage at the Ni0.8Fe0.2Ox catalyst layer using a second working electrode. The measurements demonstrate that the majority of photogenerated holes in α-Fe2O3 directly transfer to the catalyst film over a wide range of conditions and that the Ni0.8Fe0.2Ox is oxidized by photoholes to an operating potential sufficient to drive water oxidation at rates that match the photocurrent generated by the α-Fe2O3. The Ni0.8Fe0.2Ox therefore acts as both a hole-collecting contact and a catalyst for the photoelectrochemical water oxidation process. Separate measurements show that the illuminated junction photovoltage across the α-Fe2O3|Ni0.8Fe0.2Ox interface is significantly decreased by the oxidation of Ni2+ to Ni3+ and the associated increase in the Ni0.8Fe0.2Ox electrical conductivity. Finally, in sum, the results illustrate the underlying operative charge-transfer and photovoltage generation mechanisms of catalyzed photoelectrodes, thus guiding their continued improvement.},
doi = {10.1021/acscentsci.7b00310},
url = {https://www.osti.gov/biblio/1375497}, journal = {ACS Central Science},
issn = {2374-7943},
number = 9,
volume = 3,
place = {United States},
year = {2017},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1021/acscentsci.7b00310

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Cited by: 12 works
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Works referencing / citing this record:

Key Strategies to Advance the Photoelectrochemical Water Splitting Performance of α‐Fe 2 O 3 Photoanode
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A bulk adjusted linear combination of atomic orbitals (BA-LCAO) approach for nanoparticles
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Two-site H2O2 photo-oxidation on haematite photoanodes
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Thin film photoelectrodes for solar water splitting
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Strategies for enhancing the photocurrent, photovoltage, and stability of photoelectrodes for photoelectrochemical water splitting
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Role of cobalt–iron (oxy)hydroxide (CoFeO x ) as oxygen evolution catalyst on hematite photoanodes
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Transient photocurrents on catalyst-modified n-Si photoelectrodes: insight from dual-working electrode photoelectrochemistry
journal, January 2018


Interface passivation to overcome shunting in semiconductor–catalyst junctions
journal, January 2020


Tin and Oxygen-Vacancy Co-doping into Hematite Photoanode for Improved Photoelectrochemical Performances
journal, March 2020