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Title: Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO 2 in Imidazolium-Based Ionic Liquid Solutions

Real-time changes in the composition and structure of bismuth electrodes used for catalytic conversion of CO 2 into CO were examined via X-ray absorption spectroscopy (including XANES and EXAFS), electrochemical quartz crystal microbalance (EQCM) and in situ X-ray reflectivity (XR). Measurements were performed with bismuth electrodes immersed in acetonitrile (MeCN) solutions containing a 1-butyl-3-methylimidazolium ([BMIM] +) ionic liquid promoter or electrochemically inactive tetrabutylammonium supporting electrolytes (TBAPF 6 or TBAOTf). Altogether, these measurements show that bismuth electrodes are originally a mixture of bismuth oxides (including Bi 2O 3) and metallic bismuth (Bi 0), and that the reduction of oxidized bismuth species to Bi 0 is fully achieved under potentials at which CO 2 activation takes place. Furthermore, EQCM measurements conducted during cyclic voltammetry revealed that a bismuth-coated quartz crystal exhibits significant shifts in resistance (ΔR) prior to the onset of CO 2 reduction near -1.75 V vs. Ag/AgCl and pronounced hysteresis in frequency (Δf) and ΔR, which suggests significant changes in roughness or viscosity at the Bi/[BMIM] + solution interface. In situ XR performed on rhombohedral Bi (001) oriented films indicates extensive restructuring of the bismuth film cathodes takes place upon polarization to potentials more negative than -1.6 V vs. Ag/AgCl,more » which is characterized by a decrease of the Bi (001) Bragg peak intensity of ≥50% in [BMIM]OTf solutions in the presence and absence of CO 2. Over 90% of the reflectivity is recovered during the anodic half-scan, suggesting that the structural changes are mostly reversible. By contrast, such a phenomenon is not observed for thin Bi (001) oriented films in solutions of tetrabutylammonium salts that do not promote CO 2 reduction. In conclusion, these results highlight that Bi electrodes undergo significant potential-dependent chemical and structural transformations in the presence of [BMIM] + based electrolytes, including the reduction of bismuth oxide to bismuth metal, changes in roughness and near-surface viscosity.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [4] ;  [4] ;  [4] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [1]
  1. Argonne National Lab. (ANL), Lemont, IL (United States). Chemical Sciences and Engineering Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  4. Univ. of Delaware, Newark, DE (United States). Department of Chemistry and Biochemistry
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-05ER15688; AC02-98CH10886
Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 7; Journal Issue: 10; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; EQCM; EXAFS; X-ray reflectivity; XANES; XAS; bismuth; bismuth electrocatalyst; electrochemical CO2 reduction; electrode restructuring; ionic liquid
OSTI Identifier:
1422563

Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, and Fenter, Paul. Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO2 in Imidazolium-Based Ionic Liquid Solutions. United States: N. p., Web. doi:10.1021/acscatal.7b01370.
Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, & Fenter, Paul. Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO2 in Imidazolium-Based Ionic Liquid Solutions. United States. doi:10.1021/acscatal.7b01370.
Medina-Ramos, Jonnathan, Lee, Sang Soo, Fister, Timothy T., Hubaud, Aude A., Sacci, Robert L., Mullins, David R., DiMeglio, John L., Pupillo, Rachel C., Velardo, Stephanie M., Lutterman, Daniel A., Rosenthal, Joel, and Fenter, Paul. 2017. "Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO2 in Imidazolium-Based Ionic Liquid Solutions". United States. doi:10.1021/acscatal.7b01370. https://www.osti.gov/servlets/purl/1422563.
@article{osti_1422563,
title = {Structural Dynamics and Evolution of Bismuth Electrodes during Electrochemical Reduction of CO2 in Imidazolium-Based Ionic Liquid Solutions},
author = {Medina-Ramos, Jonnathan and Lee, Sang Soo and Fister, Timothy T. and Hubaud, Aude A. and Sacci, Robert L. and Mullins, David R. and DiMeglio, John L. and Pupillo, Rachel C. and Velardo, Stephanie M. and Lutterman, Daniel A. and Rosenthal, Joel and Fenter, Paul},
abstractNote = {Real-time changes in the composition and structure of bismuth electrodes used for catalytic conversion of CO2 into CO were examined via X-ray absorption spectroscopy (including XANES and EXAFS), electrochemical quartz crystal microbalance (EQCM) and in situ X-ray reflectivity (XR). Measurements were performed with bismuth electrodes immersed in acetonitrile (MeCN) solutions containing a 1-butyl-3-methylimidazolium ([BMIM]+) ionic liquid promoter or electrochemically inactive tetrabutylammonium supporting electrolytes (TBAPF6 or TBAOTf). Altogether, these measurements show that bismuth electrodes are originally a mixture of bismuth oxides (including Bi2O3) and metallic bismuth (Bi0), and that the reduction of oxidized bismuth species to Bi0 is fully achieved under potentials at which CO2 activation takes place. Furthermore, EQCM measurements conducted during cyclic voltammetry revealed that a bismuth-coated quartz crystal exhibits significant shifts in resistance (ΔR) prior to the onset of CO2 reduction near -1.75 V vs. Ag/AgCl and pronounced hysteresis in frequency (Δf) and ΔR, which suggests significant changes in roughness or viscosity at the Bi/[BMIM]+ solution interface. In situ XR performed on rhombohedral Bi (001) oriented films indicates extensive restructuring of the bismuth film cathodes takes place upon polarization to potentials more negative than -1.6 V vs. Ag/AgCl, which is characterized by a decrease of the Bi (001) Bragg peak intensity of ≥50% in [BMIM]OTf solutions in the presence and absence of CO2. Over 90% of the reflectivity is recovered during the anodic half-scan, suggesting that the structural changes are mostly reversible. By contrast, such a phenomenon is not observed for thin Bi (001) oriented films in solutions of tetrabutylammonium salts that do not promote CO2 reduction. In conclusion, these results highlight that Bi electrodes undergo significant potential-dependent chemical and structural transformations in the presence of [BMIM]+ based electrolytes, including the reduction of bismuth oxide to bismuth metal, changes in roughness and near-surface viscosity.},
doi = {10.1021/acscatal.7b01370},
journal = {ACS Catalysis},
number = 10,
volume = 7,
place = {United States},
year = {2017},
month = {9}
}