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Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting

The balance of the charge transfer and recombination kinetics of photoelectrodes governs the device efficiency for solar water splitting. Hematite (alpha-Fe2O3) is a photoanode typically used because of advantages such as its abundance, low cost, multiple convenient deposition methods, and an attrac...

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Main Authors:	Vega-Poot, Alberto, Rodriguez-Perez, Manuel, Becerril-Gonzalez, Juan, Rodriguez-Gutierrez, Ingrid, Su, Jinzhan, Rodriguez-Gattorno, Geonel, Teoh, Wey Yang, Oskam, Gerko
Format:	Article
Published:	Electrochemical Society 2022
Subjects:	QD Chemistry TP Chemical technology
Online Access:	http://eprints.um.edu.my/42247/ https://doi.org/10.1149/1945-7111/ac700b
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spelling	my.um.eprints.422472023-10-11T07:58:46Z http://eprints.um.edu.my/42247/ Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting Vega-Poot, Alberto Rodriguez-Perez, Manuel Becerril-Gonzalez, Juan Rodriguez-Gutierrez, Ingrid Su, Jinzhan Rodriguez-Gattorno, Geonel Teoh, Wey Yang Oskam, Gerko QD Chemistry TP Chemical technology The balance of the charge transfer and recombination kinetics of photoelectrodes governs the device efficiency for solar water splitting. Hematite (alpha-Fe2O3) is a photoanode typically used because of advantages such as its abundance, low cost, multiple convenient deposition methods, and an attractive bandgap energy; however, poor electrical properties prevent high solar energy to hydrogen conversion efficiencies. In this work, we evaluate and compare several strategies to address this issue, using a nanorod array morphology and incorporation of overlayers of one or more materials that favor the charge carrier transfer kinetics and reduce surface recombination. We use intensity-modulated photocurrent spectroscopy (IMPS) to evaluate these systems, and demonstrate that the presence of TiO2 and MoO x overlayers successfully suppresses surface recombination through passivation of hematite interfacial recombination sites. However, the hole transfer process at the overlayers occurs at more positive potentials due to the location of the new surface states at the overlayer-electrolyte interface. We show that the deposition of the CoPi oxygen evolution reaction co-catalyst partially addresses this disadvantage. The best efficiencies were obtained for the CoPi-TiO2/alpha-Fe2O3 and CoPi-MoO x /TiO2/alpha-Fe2O3 photoelectrodes, with internal quantum efficiencies of 0.42-0.44 under 455 nm irradiation. Electrochemical Society 2022-05-01 Article PeerReviewed Vega-Poot, Alberto and Rodriguez-Perez, Manuel and Becerril-Gonzalez, Juan and Rodriguez-Gutierrez, Ingrid and Su, Jinzhan and Rodriguez-Gattorno, Geonel and Teoh, Wey Yang and Oskam, Gerko (2022) Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting. Journal of The Electrochemical Society, 169 (5). ISSN 0013-4651, DOI https://doi.org/10.1149/1945-7111/ac700b <https://doi.org/10.1149/1945-7111/ac700b>. https://doi.org/10.1149/1945-7111/ac700b 10.1149/1945-7111/ac700b
institution	Universiti Malaya
building	UM Library
collection	Institutional Repository
continent	Asia
country	Malaysia
content_provider	Universiti Malaya
content_source	UM Research Repository
url_provider	http://eprints.um.edu.my/
topic	QD Chemistry TP Chemical technology
spellingShingle	QD Chemistry TP Chemical technology Vega-Poot, Alberto Rodriguez-Perez, Manuel Becerril-Gonzalez, Juan Rodriguez-Gutierrez, Ingrid Su, Jinzhan Rodriguez-Gattorno, Geonel Teoh, Wey Yang Oskam, Gerko Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
description	The balance of the charge transfer and recombination kinetics of photoelectrodes governs the device efficiency for solar water splitting. Hematite (alpha-Fe2O3) is a photoanode typically used because of advantages such as its abundance, low cost, multiple convenient deposition methods, and an attractive bandgap energy; however, poor electrical properties prevent high solar energy to hydrogen conversion efficiencies. In this work, we evaluate and compare several strategies to address this issue, using a nanorod array morphology and incorporation of overlayers of one or more materials that favor the charge carrier transfer kinetics and reduce surface recombination. We use intensity-modulated photocurrent spectroscopy (IMPS) to evaluate these systems, and demonstrate that the presence of TiO2 and MoO x overlayers successfully suppresses surface recombination through passivation of hematite interfacial recombination sites. However, the hole transfer process at the overlayers occurs at more positive potentials due to the location of the new surface states at the overlayer-electrolyte interface. We show that the deposition of the CoPi oxygen evolution reaction co-catalyst partially addresses this disadvantage. The best efficiencies were obtained for the CoPi-TiO2/alpha-Fe2O3 and CoPi-MoO x /TiO2/alpha-Fe2O3 photoelectrodes, with internal quantum efficiencies of 0.42-0.44 under 455 nm irradiation.
format	Article
author	Vega-Poot, Alberto Rodriguez-Perez, Manuel Becerril-Gonzalez, Juan Rodriguez-Gutierrez, Ingrid Su, Jinzhan Rodriguez-Gattorno, Geonel Teoh, Wey Yang Oskam, Gerko
author_facet	Vega-Poot, Alberto Rodriguez-Perez, Manuel Becerril-Gonzalez, Juan Rodriguez-Gutierrez, Ingrid Su, Jinzhan Rodriguez-Gattorno, Geonel Teoh, Wey Yang Oskam, Gerko
author_sort	Vega-Poot, Alberto
title	Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
title_short	Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
title_full	Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
title_fullStr	Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
title_full_unstemmed	Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
title_sort	charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting
publisher	Electrochemical Society
publishDate	2022
url	http://eprints.um.edu.my/42247/ https://doi.org/10.1149/1945-7111/ac700b
_version_	1781704615601897472
score	13.211869

Charge dynamics at surface-modified, nanostructured hematite photoelectrodes for solar water splitting

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