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

[Image: see text] 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...

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Autores principales: Qiu, Jingjing, Hajibabaei, Hamed, Nellist, Michael R., Laskowski, Forrest A. L., Hamann, Thomas W., Boettcher, Shannon W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2017
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620968/
https://www.ncbi.nlm.nih.gov/pubmed/28979943
http://dx.doi.org/10.1021/acscentsci.7b00310
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author Qiu, Jingjing
Hajibabaei, Hamed
Nellist, Michael R.
Laskowski, Forrest A. L.
Hamann, Thomas W.
Boettcher, Shannon W.
author_facet Qiu, Jingjing
Hajibabaei, Hamed
Nellist, Michael R.
Laskowski, Forrest A. L.
Hamann, Thomas W.
Boettcher, Shannon W.
author_sort Qiu, Jingjing
collection PubMed
description [Image: see text] 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(2)O(3), in contact with one of the fastest known water oxidation catalysts, Ni(0.8)Fe(0.2)O(x), by directly measuring/controlling the current and/or voltage at the Ni(0.8)Fe(0.2)O(x) catalyst layer using a second working electrode. The measurements demonstrate that the majority of photogenerated holes in α-Fe(2)O(3) directly transfer to the catalyst film over a wide range of conditions and that the Ni(0.8)Fe(0.2)O(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(2)O(3). The Ni(0.8)Fe(0.2)O(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(2)O(3)|Ni(0.8)Fe(0.2)O(x) interface is significantly decreased by the oxidation of Ni(2+) to Ni(3+) and the associated increase in the Ni(0.8)Fe(0.2)O(x) electrical conductivity. In sum, the results illustrate the underlying operative charge-transfer and photovoltage generation mechanisms of catalyzed photoelectrodes, thus guiding their continued improvement.
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spelling pubmed-56209682017-10-04 Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite Qiu, Jingjing Hajibabaei, Hamed Nellist, Michael R. Laskowski, Forrest A. L. Hamann, Thomas W. Boettcher, Shannon W. ACS Cent Sci [Image: see text] 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(2)O(3), in contact with one of the fastest known water oxidation catalysts, Ni(0.8)Fe(0.2)O(x), by directly measuring/controlling the current and/or voltage at the Ni(0.8)Fe(0.2)O(x) catalyst layer using a second working electrode. The measurements demonstrate that the majority of photogenerated holes in α-Fe(2)O(3) directly transfer to the catalyst film over a wide range of conditions and that the Ni(0.8)Fe(0.2)O(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(2)O(3). The Ni(0.8)Fe(0.2)O(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(2)O(3)|Ni(0.8)Fe(0.2)O(x) interface is significantly decreased by the oxidation of Ni(2+) to Ni(3+) and the associated increase in the Ni(0.8)Fe(0.2)O(x) electrical conductivity. In sum, the results illustrate the underlying operative charge-transfer and photovoltage generation mechanisms of catalyzed photoelectrodes, thus guiding their continued improvement. American Chemical Society 2017-08-17 2017-09-27 /pmc/articles/PMC5620968/ /pubmed/28979943 http://dx.doi.org/10.1021/acscentsci.7b00310 Text en Copyright © 2017 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle 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
title Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite
title_full Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite
title_fullStr Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite
title_full_unstemmed Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite
title_short Direct in Situ Measurement of Charge Transfer Processes During Photoelectrochemical Water Oxidation on Catalyzed Hematite
title_sort direct in situ measurement of charge transfer processes during photoelectrochemical water oxidation on catalyzed hematite
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620968/
https://www.ncbi.nlm.nih.gov/pubmed/28979943
http://dx.doi.org/10.1021/acscentsci.7b00310
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