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Title: Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl 2O 4 catalysts

Supported single atoms provide an opportunity to design new heterogeneous catalysts while optimizing the utilization of noble metals. However, identification of the active single-atom structure is required for understanding the reaction mechanism and guiding catalyst design. Here, we use in situ infrared spectroscopy, operando X-ray absorption spectroscopy and quantum chemical calculations to identify the active single-atom complex as well as the resting state of the Ir/MgAl 2O 4 catalysts during the low-temperature CO oxidation. In contrast to poisoning of iridium nanoparticles by CO, here we show that the formation of Ir(CO) on single atoms results in a different reaction mechanism and high activity for low-temperature CO oxidation. Furthermore this is due to the ability of single atoms to coordinate with multiple ligands, where Ir(CO) provides an interfacial site for facile O 2 activation between Ir and Al and lowers the reaction barrier between gas-phase CO(g) and *O in Ir(CO)(O) through an Eley–Rideal mechanism.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [3] ;  [3] ;  [3] ;  [2] ;  [1] ; ORCiD logo [1]
  1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Nature Catalysis
Additional Journal Information:
Journal Volume: 2; Journal Issue: 2; Journal ID: ISSN 2520-1158
Publisher:
Springer Nature
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1503098

Lu, Yubing, Wang, Jiamin, Yu, Liang, Kovarik, Libor, Zhang, Xiwen, Hoffman, Adam S., Gallo, Alessandro, Bare, Simon R., Sokaras, Dimosthenis, Kroll, Thomas, Dagle, Vanessa, Xin, Hongliang, and Karim, Ayman M.. Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts. United States: N. p., Web. doi:10.1038/s41929-018-0192-4.
Lu, Yubing, Wang, Jiamin, Yu, Liang, Kovarik, Libor, Zhang, Xiwen, Hoffman, Adam S., Gallo, Alessandro, Bare, Simon R., Sokaras, Dimosthenis, Kroll, Thomas, Dagle, Vanessa, Xin, Hongliang, & Karim, Ayman M.. Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts. United States. doi:10.1038/s41929-018-0192-4.
Lu, Yubing, Wang, Jiamin, Yu, Liang, Kovarik, Libor, Zhang, Xiwen, Hoffman, Adam S., Gallo, Alessandro, Bare, Simon R., Sokaras, Dimosthenis, Kroll, Thomas, Dagle, Vanessa, Xin, Hongliang, and Karim, Ayman M.. 2018. "Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts". United States. doi:10.1038/s41929-018-0192-4.
@article{osti_1503098,
title = {Identification of the active complex for CO oxidation over single-atom Ir-on-MgAl2O4 catalysts},
author = {Lu, Yubing and Wang, Jiamin and Yu, Liang and Kovarik, Libor and Zhang, Xiwen and Hoffman, Adam S. and Gallo, Alessandro and Bare, Simon R. and Sokaras, Dimosthenis and Kroll, Thomas and Dagle, Vanessa and Xin, Hongliang and Karim, Ayman M.},
abstractNote = {Supported single atoms provide an opportunity to design new heterogeneous catalysts while optimizing the utilization of noble metals. However, identification of the active single-atom structure is required for understanding the reaction mechanism and guiding catalyst design. Here, we use in situ infrared spectroscopy, operando X-ray absorption spectroscopy and quantum chemical calculations to identify the active single-atom complex as well as the resting state of the Ir/MgAl2O4 catalysts during the low-temperature CO oxidation. In contrast to poisoning of iridium nanoparticles by CO, here we show that the formation of Ir(CO) on single atoms results in a different reaction mechanism and high activity for low-temperature CO oxidation. Furthermore this is due to the ability of single atoms to coordinate with multiple ligands, where Ir(CO) provides an interfacial site for facile O2 activation between Ir and Al and lowers the reaction barrier between gas-phase CO(g) and *O in Ir(CO)(O) through an Eley–Rideal mechanism.},
doi = {10.1038/s41929-018-0192-4},
journal = {Nature Catalysis},
number = 2,
volume = 2,
place = {United States},
year = {2018},
month = {12}
}

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