Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics

Hematite is a promising photoanode for solar water splitting by photoelectrochemical (PEC) cells, but its performance is limited by the slow kinetics of water oxidation reaction or oxygen evolution reaction (OER). Surface modification of hematite photoanodes with a suitable water oxidation cocatalys...

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Main Authors: Ahmed, Mahmoud Gamal, Zhang, Mengyuan, Tay, Ying Fan, Chiam, Sing Yang, Wong, Lydia Helena
Other Authors: School of Materials Science and Engineering
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/145038
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spelling sg-ntu-dr.10356-1450382023-07-14T15:48:46Z Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics Ahmed, Mahmoud Gamal Zhang, Mengyuan Tay, Ying Fan Chiam, Sing Yang Wong, Lydia Helena School of Materials Science and Engineering Solar Fuels Laboratory Science::Chemistry::Physical chemistry Photoelectrochemical Water Splitting Hematite Photoanode Hematite is a promising photoanode for solar water splitting by photoelectrochemical (PEC) cells, but its performance is limited by the slow kinetics of water oxidation reaction or oxygen evolution reaction (OER). Surface modification of hematite photoanodes with a suitable water oxidation cocatalyst is a key strategy for improving the kinetics of water oxidation. In this study, a CeOx overlayer is deposited on the surface of the hematite photoanode by a water‐based solution method with ceric ammonium nitrate (CAN) followed by heat treatment. The photocurrent of CeOx‐modified hematite is 3 times higher than that of pristine hematite (at 1.23 V vs. RHE) under AM 1.5G, 1 sun conditions. Through hole‐scavenger measurements, Tafel plot analysis, and electrochemical impedance spectroscopy, it is concluded that CeOx overlayer increases the hole injection efficiency, improves the surface catalytic activity, and enhances charge transfer across the photoanode/electrolyte interface. These observations are attributed to the synergistic effects of Ce3+/Ce4+ redox species in CeOx and the oxygen vacancies. This work elucidates the role of CeOx as an efficient cocatalyst overlayer to improve the OER kinetics of photoanodes. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version This research is partially supported by grants from the National Research Foundation, Prime Min ister’s Office, Sin g ap o re un der its Campus of Research Excellence and Technological Enterprise (CREATE) programme and Ministry of Education (MOE) Tier 2 Project (MOE2016-T2-1-030). 2020-12-09T05:24:52Z 2020-12-09T05:24:52Z 2020 Journal Article Ahmed, M. G., Zhang, M., Tay, Y. F., Chiam, S. Y., & Wong, Lydia H. (2020). Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics. ChemSusChem, 13(20), 5489-5496. doi:10.1002/cssc.202001135 1864-564X https://hdl.handle.net/10356/145038 10.1002/cssc.202001135 20 13 5489 5496 en MOE2016-T2-1-030 ChemSusChem This is the accepted version of the following article: Ahmed, M. G., Zhang, M., Tay, Y. F., Chiam, S. Y., & Wong, Lydia H. (2020). Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics. ChemSusChem, 13(20), 5489-5496. doi:10.1002/cssc.202001135, which has been published in final form at https://doi.org/10.1002/cssc.202001135. This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving Policy [https://authorservices.wiley.com/authorresources/Journal-Authors/licensing/self-archiving.html]. application/pdf application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Chemistry::Physical chemistry
Photoelectrochemical Water Splitting
Hematite Photoanode
spellingShingle Science::Chemistry::Physical chemistry
Photoelectrochemical Water Splitting
Hematite Photoanode
Ahmed, Mahmoud Gamal
Zhang, Mengyuan
Tay, Ying Fan
Chiam, Sing Yang
Wong, Lydia Helena
Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
description Hematite is a promising photoanode for solar water splitting by photoelectrochemical (PEC) cells, but its performance is limited by the slow kinetics of water oxidation reaction or oxygen evolution reaction (OER). Surface modification of hematite photoanodes with a suitable water oxidation cocatalyst is a key strategy for improving the kinetics of water oxidation. In this study, a CeOx overlayer is deposited on the surface of the hematite photoanode by a water‐based solution method with ceric ammonium nitrate (CAN) followed by heat treatment. The photocurrent of CeOx‐modified hematite is 3 times higher than that of pristine hematite (at 1.23 V vs. RHE) under AM 1.5G, 1 sun conditions. Through hole‐scavenger measurements, Tafel plot analysis, and electrochemical impedance spectroscopy, it is concluded that CeOx overlayer increases the hole injection efficiency, improves the surface catalytic activity, and enhances charge transfer across the photoanode/electrolyte interface. These observations are attributed to the synergistic effects of Ce3+/Ce4+ redox species in CeOx and the oxygen vacancies. This work elucidates the role of CeOx as an efficient cocatalyst overlayer to improve the OER kinetics of photoanodes.
author2 School of Materials Science and Engineering
author_facet School of Materials Science and Engineering
Ahmed, Mahmoud Gamal
Zhang, Mengyuan
Tay, Ying Fan
Chiam, Sing Yang
Wong, Lydia Helena
format Article
author Ahmed, Mahmoud Gamal
Zhang, Mengyuan
Tay, Ying Fan
Chiam, Sing Yang
Wong, Lydia Helena
author_sort Ahmed, Mahmoud Gamal
title Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
title_short Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
title_full Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
title_fullStr Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
title_full_unstemmed Surface modification of hematite photoanodes with CeOx cocatalyst for improved photoelectrochemical water oxidation kinetics
title_sort surface modification of hematite photoanodes with ceox cocatalyst for improved photoelectrochemical water oxidation kinetics
publishDate 2020
url https://hdl.handle.net/10356/145038
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