Defect Engineering of WO3 by Rapid Flame Reduction for Efficient Photoelectrochemical Conversion of Methane into Liquid Oxygenates

Ho Kun Woo; Ankit Kumar Gautam; Jaxiry S. Barroso-Martínez; Arthur P. Baddorf; Kai Zhou; Yoon Young Choi; Jiajun He; Alexander V. Mironenko; Joaquín Rodríguez-López; Lili Cai

doi:10.1021/acs.nanolett.3c03131

Defect Engineering of WO₃ by Rapid Flame Reduction for Efficient Photoelectrochemical Conversion of Methane into Liquid Oxygenates

Ho Kun Woo, Ankit Kumar Gautam, Jaxiry S. Barroso-Martínez, Arthur P. Baddorf, Kai Zhou, Yoon Young Choi, Jiajun He, Alexander V. Mironenko, Joaquín Rodríguez-López, Lili Cai

Scanning Tunneling Microscopy Group

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Photoelectrochemical (PEC) conversion is a promising way to use methane (CH₄) as a chemical building block without harsh conditions. However, the PEC conversion of CH₄ to value-added chemicals remains challenging due to the thermodynamically favorable overoxidation of CH₄. Here, we report WO₃ nanotube (NT) photoelectrocatalysts for PEC CH₄ conversion with high liquid product selectivity through defect engineering. By tuning the flame reduction treatment, we carefully controlled the oxygen vacancies of WO₃ NTs. The optimally reduced WO₃ NTs suppressed overoxidation of CH₄ showing a high total C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol cm^-2 h^-1. Scanning electrochemical microscopy revealed that oxygen vacancies can restrain the production of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates to CO₂. Additionally, band diagram analysis and computational studies elucidated that oxygen vacancies thermodynamically suppress overoxidation. This work introduces a strategy for understanding and controlling the selectivity of photoelectrocatalysts for direct conversion of CH₄ to liquids.

Original language	English
Pages (from-to)	11493-11500
Number of pages	8
Journal	Nano Letters
Volume	23
Issue number	24
DOIs	https://doi.org/10.1021/acs.nanolett.3c03131
State	Published - Dec 27 2023

Funding

This work was supported by the donors of the ACS Petroleum Research Fund (PRF) under Doctoral New Investigator Grant 65618-DNI5. L.C. served as Principal Investigator on ACS PRF 65618-DNI5 that provided support for H.K.W. This research was also financially supported by the startup fund from University of Illinois at Urbana-Champaign. J.S.B.-M. and J.R.-L. acknowledge support from the National Science Foundation under CHE Grant 2004054. H.K.W. acknowledges support from the TechnipFMC Fellowship. 1H NMR was carried out in the School of Chemical Sciences NMR Lab at the University of Illinois at Urbana-Champaign. The authors acknowledge Dr. D. L. Olson of the University of Illinois at Urbana-Champaign for the NMR analysis. Major funding for the Bruker EMXPlus instrument was provided by National Science Foundation Grant 1726244 (2017) to the School of Chemical Sciences EPR lab at the University of Illinois at Urbana-Champaign. TEM, XRD, SEM, UV-vis, and XPS were conducted in the Materials Research Laboratory at the University of Illinois at Urbana-Champaign. UV photoemission spectroscopy research was conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy Office of Science User Facility at Oak Ridge National Laboratory. This work was supported by the donors of the ACS Petroleum Research Fund (PRF) under Doctoral New Investigator Grant 65618-DNI5. L.C. served as Principal Investigator on ACS PRF 65618-DNI5 that provided support for H.K.W. This research was also financially supported by the startup fund from University of Illinois at Urbana-Champaign. J.S.B.-M. and J.R.-L. acknowledge support from the National Science Foundation under CHE Grant 2004054. H.K.W. acknowledges support from the TechnipFMC Fellowship. H NMR was carried out in the School of Chemical Sciences NMR Lab at the University of Illinois at Urbana-Champaign. The authors acknowledge Dr. D. L. Olson of the University of Illinois at Urbana-Champaign for the NMR analysis. Major funding for the Bruker EMXPlus instrument was provided by National Science Foundation Grant 1726244 (2017) to the School of Chemical Sciences EPR lab at the University of Illinois at Urbana-Champaign. TEM, XRD, SEM, UV–vis, and XPS were conducted in the Materials Research Laboratory at the University of Illinois at Urbana-Champaign. UV photoemission spectroscopy research was conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a U.S. Department of Energy Office of Science User Facility at Oak Ridge National Laboratory. 1

Funders	Funder number
TechnipFMC	1726244
National Science Foundation
Division of Chemistry	2004054
University of Illinois at Urbana-Champaign
Office of Science
Oak Ridge National Laboratory
American Chemical Society Petroleum Research Fund	65618-DNI5

Keywords

defect engineering
methane oxidation
photoelectrochemical conversion
rapid flame reduction
tungsten trioxide

Access to Document

10.1021/acs.nanolett.3c03131

Cite this

Woo, H. K., Gautam, A. K., Barroso-Martínez, J. S., Baddorf, A. P., Zhou, K., Choi, Y. Y., He, J., Mironenko, A. V., Rodríguez-López, J., & Cai, L. (2023). Defect Engineering of WO₃ by Rapid Flame Reduction for Efficient Photoelectrochemical Conversion of Methane into Liquid Oxygenates. Nano Letters, 23(24), 11493-11500. https://doi.org/10.1021/acs.nanolett.3c03131

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abstract = "Photoelectrochemical (PEC) conversion is a promising way to use methane (CH4) as a chemical building block without harsh conditions. However, the PEC conversion of CH4 to value-added chemicals remains challenging due to the thermodynamically favorable overoxidation of CH4. Here, we report WO3 nanotube (NT) photoelectrocatalysts for PEC CH4 conversion with high liquid product selectivity through defect engineering. By tuning the flame reduction treatment, we carefully controlled the oxygen vacancies of WO3 NTs. The optimally reduced WO3 NTs suppressed overoxidation of CH4 showing a high total C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol cm-2 h-1. Scanning electrochemical microscopy revealed that oxygen vacancies can restrain the production of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates to CO2. Additionally, band diagram analysis and computational studies elucidated that oxygen vacancies thermodynamically suppress overoxidation. This work introduces a strategy for understanding and controlling the selectivity of photoelectrocatalysts for direct conversion of CH4 to liquids.",

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AU - Zhou, Kai

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N2 - Photoelectrochemical (PEC) conversion is a promising way to use methane (CH4) as a chemical building block without harsh conditions. However, the PEC conversion of CH4 to value-added chemicals remains challenging due to the thermodynamically favorable overoxidation of CH4. Here, we report WO3 nanotube (NT) photoelectrocatalysts for PEC CH4 conversion with high liquid product selectivity through defect engineering. By tuning the flame reduction treatment, we carefully controlled the oxygen vacancies of WO3 NTs. The optimally reduced WO3 NTs suppressed overoxidation of CH4 showing a high total C1 liquid selectivity of 69.4% and a production rate of 0.174 μmol cm-2 h-1. Scanning electrochemical microscopy revealed that oxygen vacancies can restrain the production of hydroxyl radicals, which, in excess, could further oxidize C1 intermediates to CO2. Additionally, band diagram analysis and computational studies elucidated that oxygen vacancies thermodynamically suppress overoxidation. This work introduces a strategy for understanding and controlling the selectivity of photoelectrocatalysts for direct conversion of CH4 to liquids.

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