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Title: Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide

Abstract

The electrochemical reduction of CO 2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO 2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably for HCOO , C 2H 4, and C 2H 5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO 2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity withmore » cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.« less

Authors:
 [1];  [2];  [1];  [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [1]
  1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1390621
Grant/Contract Number:
AC02-76SF00515; DGE-0802270; AC02-05CH11231; SC0004993
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 32; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; electrochemical reduction; CO2; copper; silver

Citation Formats

Resasco, Joaquin, Chen, Leanne D., Clark, Ezra, Tsai, Charlie, Hahn, Christopher, Jaramillo, Thomas F., Chan, Karen, and Bell, Alexis T. Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide. United States: N. p., 2017. Web. doi:10.1021/jacs.7b06765.
Resasco, Joaquin, Chen, Leanne D., Clark, Ezra, Tsai, Charlie, Hahn, Christopher, Jaramillo, Thomas F., Chan, Karen, & Bell, Alexis T. Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide. United States. doi:10.1021/jacs.7b06765.
Resasco, Joaquin, Chen, Leanne D., Clark, Ezra, Tsai, Charlie, Hahn, Christopher, Jaramillo, Thomas F., Chan, Karen, and Bell, Alexis T. 2017. "Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide". United States. doi:10.1021/jacs.7b06765.
@article{osti_1390621,
title = {Promoter Effects of Alkali Metal Cations on the Electrochemical Reduction of Carbon Dioxide},
author = {Resasco, Joaquin and Chen, Leanne D. and Clark, Ezra and Tsai, Charlie and Hahn, Christopher and Jaramillo, Thomas F. and Chan, Karen and Bell, Alexis T.},
abstractNote = {The electrochemical reduction of CO2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably for HCOO–, C2H4, and C2H5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.},
doi = {10.1021/jacs.7b06765},
journal = {Journal of the American Chemical Society},
number = 32,
volume = 139,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 3works
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  • The electrochemical reduction of CO 2 is known to be influenced by the identity of the alkali metal cation in the electrolyte; however, a satisfactory explanation for this phenomenon has not been developed. Here we present the results of experimental and theoretical studies aimed at elucidating the effects of electrolyte cation size on the intrinsic activity and selectivity of metal catalysts for the reduction of CO 2. Experiments were conducted under conditions where the influence of electrolyte polarization is minimal in order to show that cation size affects the intrinsic rates of formation of certain reaction products, most notably formore » HCOO , C 2H 4, and C 2H 5OH over Cu(100)- and Cu(111)-oriented thin films, and for CO and HCOO– over polycrystalline Ag and Sn. Interpretation of the findings for CO 2 reduction was informed by studies of the reduction of glyoxal and CO, key intermediates along the reaction pathway to final products. Density functional theory calculations show that the alkali metal cations influence the distribution of products formed as a consequence of electrostatic interactions between solvated cations present at the outer Helmholtz plane and adsorbed species having large dipole moments. As a result, the observed trends in activity with cation size are attributed to an increase in the concentration of cations at the outer Helmholtz plane with increasing cation size.« less
    Cited by 3
  • The behavior of the methanol and higher alcohol (HAS) syntheses as a function of catalyst promoter concentration, CO{sub 2} feed gas concentration, and methanol feed gas concentration has been investigated over a Cu/ZnO/Cr{sub 2}O{sub 3} catalyst at 10 MPa and 285-315 C. In the presence of CO{sub 2} in the feed gas, the methanol and HAS yields are greater for the unpromoted catalyst than the 0.5% K{sub 2}CO{sub 3}-promoted catalyst. The methanol and HAS yields also reach a maximum as the CO{sub 2} concentration increases for both catalysts. In the absence of CO{sub 2}, both the methanol and HAS yieldsmore » reach a maximum as the K{sub 2}CO{sub 3} promoter concentration increases. The complex behavior results from the ability of these catalysts to incorporate CO, CO{sub 2}, and methanol into higher alcohols, on at least two different types of catalytic sites. It is suggested that CO{sub 2} participates directly in HAS on copper sites while alkali/copper interfacial sites are involved in converting CO. Higher alcohol production is therefore very sensitive to the feed gas composition and the components and composition of the catalyst.« less
  • Increases in energy demand and in chemical production, together with the rise in CO 2 levels in the atmosphere, motivate the development of renewable energy sources. Electrochemical CO 2 reduction to fuels and chemicals is an appealing alternative to traditional pathways to fuels and chemicals due to its intrinsic ability to couple to solar and wind energy sources. Formate (HCOO ) is a key chemical for many industries; however, greater understanding is needed regarding the mechanism and key intermediates for HCOO production. This work reports a joint experimental and theoretical investigation of the electrochemical reduction of CO 2 tomore » HCOO on polycrystalline Sn surfaces, which have been identified as promising catalysts for selectively producing HCOO . Our results show that Sn electrodes produce HCOO , carbon monoxide (CO), and hydrogen (H 2) across a range of potentials and that HCOO production becomes favored at potentials more negative than –0.8 V vs RHE, reaching a maximum Faradaic efficiency of 70% at –0.9 V vs RHE. Scaling relations for Sn and other transition metals are examined using experimental current densities and density functional theory (DFT) binding energies. While *COOH was determined to be the key intermediate for CO production on metal surfaces, we suggest that it is unlikely to be the primary intermediate for HCOO production. Instead, *OCHO is suggested to be the key intermediate for the CO 2RR to HCOO transformation, and Sn’s optimal *OCHO binding energy supports its high selectivity for HCOO . Lastly, these results suggest that oxygen-bound intermediates are critical to understand the mechanism of CO 2 reduction to HCOO on metal surfaces.« less
  • Simultaneous reduction of carbon dioxide and nitrate ions was examined at gas-diffusion electrodes with various catalysts (Cr, Mo, Mn, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, An, Cd, In, Tl, Sn and Pb). The formation of urea, CO, formic acid, nitrite ions, and ammonia at the gas-diffusion electrodes with groups 11--14 catalysts, except for Au, was found in the simultaneous reduction. The maximum faradaic efficiency of urea formation on Zn catalysts is approximately 35% at {minus}1.75 V. The formation of urea at the gas-diffusion electrodes with groups 6--10 catalysts was not found in the simultaneous reduction ofmore » CO{sub 2} and nitrate. Relationship of the ability for urea formation to the ability for CO and NH{sub 3} formation was investigated with various catalysts. The ability for urea formation with the catalysts depends on the ability for CO and NH{sub 3} formation. The catalysts with high ability for CO and NU{sub 3} formation could form large amounts of CO-like and ammonia-like precursors. The faradaic efficiency of urea formation for simultaneous reduction with nitrate ions is lower than that with nitrite ions. This result seems to be related to the ability for ammonia-like precursor formation.« less