Title: Optimizing C–C Coupling on Oxide-Derived Copper Catalysts for Electrochemical CO₂ Reduction

Abstract

Here, copper electrodes, prepared by reduction of oxidized metallic copper, have been reported to exhibit higher activity for the electrochemical reduction of CO₂ and better selectivity toward C₂ and C₃ (C₂₊) products than metallic copper that has not been preoxidized. We report here an investigation of the effects of four different preparations of oxide-derived electrocatalysts on their activity and selectivity for CO₂ reduction, with particular attention given to the selectivity to C₂₊ products. All catalysts were tested for CO₂ reduction in 0.1 M KHCO₃ and 0.1 M CsHCO₃ at applied voltages in the range from –0.7 to –1.0 V vs RHE. The best performing oxide-derived catalysts show up to ~70% selectivity to C₂₊ products and only ~3% selectivity to C₁ products at –1.0 V vs RHE when CsHCO₃ is used as the electrolyte. In contrast, the selectivity to C₂₊ products decreases to ~56% for the same catalysts tested in KHCO₃. By studying all catalysts under identical conditions, the key factors affecting product selectivity could be discerned. These efforts reveal that the surface area of the oxide-derived layer is a critical parameter affecting selectivity. A high selectivity to C₂₊ products is attained at an overpotential of –1 V vs RHE bymore » operating at a current density sufficiently high to achieve a moderately high pH near the catalyst surface but not so high as to cause a significant reduction in the local concentration of CO₂. On the basis of recent theoretical studies, a high pH suppresses the formation of C₁ relative to C₂₊ products. At the same time, however, a high local CO₂ concentration is necessary for the formation of C₂₊ products.« less

Authors:

Lum, Yanwei ^[1]; Yue, Binbin ^[2]; Lobaccaro, Peter ^[1]; Bell, Alexis T.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5738-4645"

Ager, Joel W.  ^[1]

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• Search DOE PAGES for ORCID "0000-0001-9334-9751"

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
2. Center for High Pressure Science and Technology Advanced Research, Shanghai (People's Republic of China); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

Thu Jul 06 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division

OSTI Identifier:

1418297

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 121; Journal Issue: 26; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY