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Title: Subsurface oxide plays a critical role in CO 2 activation by Cu(111) surfaces to form chemisorbed CO 2, the first step in reduction of CO 2

Abstract

A national priority is to convert CO 2 into high-value chemical products such as liquid fuels. Because current electrocatalysts are not adequate, we aim to discover new catalysts by obtaining a detailed understanding of the initial steps of CO 2 electroreduction on copper surfaces, the best current catalysts. Using ambient pressure X-ray photoelectron spectroscopy interpreted with quantum mechanical prediction of the structures and free energies, we show that the presence of a thin suboxide structure below the copper surface is essential to bind the CO 2 in the physisorbed configuration at 298 K, and we show that this suboxide is essential for converting to the chemisorbed CO 2 in the presence of water as the first step toward CO 2 reduction products such as formate and CO. This optimum suboxide leads to both neutral and charged Cu surface sites, providing fresh insights into how to design improved carbon dioxide reduction catalysts.

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2];  [1];  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1363709
Alternate Identifier(s):
OSTI ID: 1408437
Grant/Contract Number:
AC02-05CH11231; SC0004993
Resource Type:
Journal Article: Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 26; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; CO2 reduction; suboxide copper; ambient pressure XPS; density functional theory; M06L

Citation Formats

Favaro, Marco, Xiao, Hai, Cheng, Tao, Goddard, William A., Yano, Junko, and Crumlin, Ethan J. Subsurface oxide plays a critical role in CO2 activation by Cu(111) surfaces to form chemisorbed CO2, the first step in reduction of CO2. United States: N. p., 2017. Web. doi:10.1073/pnas.1701405114.
Favaro, Marco, Xiao, Hai, Cheng, Tao, Goddard, William A., Yano, Junko, & Crumlin, Ethan J. Subsurface oxide plays a critical role in CO2 activation by Cu(111) surfaces to form chemisorbed CO2, the first step in reduction of CO2. United States. doi:10.1073/pnas.1701405114.
Favaro, Marco, Xiao, Hai, Cheng, Tao, Goddard, William A., Yano, Junko, and Crumlin, Ethan J. Mon . "Subsurface oxide plays a critical role in CO2 activation by Cu(111) surfaces to form chemisorbed CO2, the first step in reduction of CO2". United States. doi:10.1073/pnas.1701405114.
@article{osti_1363709,
title = {Subsurface oxide plays a critical role in CO2 activation by Cu(111) surfaces to form chemisorbed CO2, the first step in reduction of CO2},
author = {Favaro, Marco and Xiao, Hai and Cheng, Tao and Goddard, William A. and Yano, Junko and Crumlin, Ethan J.},
abstractNote = {A national priority is to convert CO2 into high-value chemical products such as liquid fuels. Because current electrocatalysts are not adequate, we aim to discover new catalysts by obtaining a detailed understanding of the initial steps of CO2 electroreduction on copper surfaces, the best current catalysts. Using ambient pressure X-ray photoelectron spectroscopy interpreted with quantum mechanical prediction of the structures and free energies, we show that the presence of a thin suboxide structure below the copper surface is essential to bind the CO2 in the physisorbed configuration at 298 K, and we show that this suboxide is essential for converting to the chemisorbed CO2 in the presence of water as the first step toward CO2 reduction products such as formate and CO. This optimum suboxide leads to both neutral and charged Cu surface sites, providing fresh insights into how to design improved carbon dioxide reduction catalysts.},
doi = {10.1073/pnas.1701405114},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 26,
volume = 114,
place = {United States},
year = {Mon Jun 12 00:00:00 EDT 2017},
month = {Mon Jun 12 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1073/pnas.1701405114

Citation Metrics:
Cited by: 5works
Citation information provided by
Web of Science

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  • A national priority is to convert CO 2 into high-value chemical products such as liquid fuels. Because current electrocatalysts are not adequate, we aim to discover new catalysts by obtaining a detailed understanding of the initial steps of CO 2 electroreduction on copper surfaces, the best current catalysts. Using ambient pressure X-ray photoelectron spectroscopy interpreted with quantum mechanical prediction of the structures and free energies, we show that the presence of a thin suboxide structure below the copper surface is essential to bind the CO 2 in the physisorbed configuration at 298 K, and we show that this suboxide ismore » essential for converting to the chemisorbed CO 2 in the presence of water as the first step toward CO 2 reduction products such as formate and CO. This optimum suboxide leads to both neutral and charged Cu surface sites, providing fresh insights into how to design improved carbon dioxide reduction catalysts.« less
  • The role of the interface between a metal and oxide (CeO x–Cu and ZnO–Cu) is critical to the production of methanol through the hydrogenation of CO 2 (CO 2 + 3H 2 → CH 3OH + H 2O). The deposition of nanoparticles of CeO x or ZnO on Cu(111), θ oxi < 0.3 monolayer, produces highly active catalysts for methanol synthesis. The catalytic activity of these systems increases in the sequence: Cu(111) < ZnO/Cu(111) < CeO x/Cu(111). The apparent activation energy for the CO 2 → CH 3OH conversion decreases from 25 kcal/mol on Cu(111) to 16 kcal/mol on ZnO/Cu(111)more » and 13 kcal/mol on CeO x/Cu(111). The surface chemistry of the highly active CeO x–Cu(111) interface was investigated using ambient pressure X-ray photoemission spectroscopy (AP-XPS) and infrared reflection absorption spectroscopy (AP-IRRAS). Both techniques point to the formation of formates (HCOO ) and carboxylates (CO 2 δ–) during the reaction. Our results show an active state of the catalyst rich in Ce 3+ sites which stabilize a CO 2 δ– species that is an essential intermediate for the production of methanol. Furthermore, the inverse oxide/metal configuration favors strong metal–oxide interactions and makes possible reaction channels not seen in conventional metal/oxide catalysts.« less
  • The results of kinetic tests and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) show the important role played by a ZnO–copper interface in the generation of CO and the synthesis of methanol from CO 2 hydrogenation. The deposition of nanoparticles of ZnO on Cu(100) and Cu(111), θ oxi < 0.3 monolayer, produces highly active catalysts. The catalytic activity of these systems increases in the sequence: Cu(111) < Cu(100) < ZnO/Cu(111) < ZnO/Cu(100). The structure of the copper substrate influences the catalytic performance of a ZnO–copper interface. Furthermore, size and metal–oxide interactions affect the chemical and catalytic properties of the oxide making themore » supported nanoparticles different from bulk ZnO. The formation of a ZnO–copper interface favors the binding and conversion of CO 2 into a formate intermediate that is stable on the catalyst surface up to temperatures above 500 K. Alloys of Zn with Cu(111) and Cu(100) were not stable at the elevated temperatures (500–600 K) used for the CO 2 hydrogenation reaction. However, reaction with CO 2 oxidized the zinc, enhancing its stability over the copper substrates.« less
  • Studies with a series of M-CeO 2(111) {M= Co, Ni, Cu} surfaces indicate that metal-oxide interactions can play a very important role for the activation of methane and its reforming with CO 2 at relatively low temperatures (600-700 K). Among the systems examined, Co-CeO 2(111) exhibits the best performance and Cu-CeO 2(111) has negligible activity. Experiments using ambient pressure XPS indicate that methane dissociates on Co-CeO2(111), at temperatures as low as 300 K, generating CH x and CO x species on the catalyst surface. The results of density-functional calculations show a reduction in the methane activation barrier from 1.07 eVmore » on Co(0001) to 0.87 eV on Co 2+/CeO 2(111), and to only 0.05 eV on Co 0/CeO 2-x(111). At 700 K, under methane dry reforming conditions, CO 2 dissociates on the oxide surface and a catalytic cycle is established without coke deposition. In conclusion, a significant part of the CH x formed on the Co 0/CeO 2-x (111) catalyst recombines to yield ethane or ethylene.« less
    Cited by 1
  • The results of core-level photoemission indicate that Ni-CeO 2(111) surfaces with small or medium coverages of nickel are able to activate methane at 300 K, producing adsorbed CH x and CO x (x = 2, 3) groups. Calculations based on density functional theory predict a relatively low activation energy of 0.6–0.7 eV for the cleavage of the first C–H bond in the adsorbed methane molecule. Ni and O centers of ceria work in a cooperative way in the dissociation of the C–H bond at room temperature, where a low Ni loading is crucial for the catalyst activity and stability. Themore » strong electronic perturbations in the Ni nanoparticles produced by the ceria supports of varying natures, such as stoichiometric and reduced, result in a drastic change in their chemical properties toward methane adsorption and dissociation as well as the dry reforming of methane reaction. Lastly, the coverage of Ni has a drastic effect on the ability of the system to dissociate methane and catalyze the dry re-forming process.« less