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Dramatic HER Suppression on Ag Electrodes via Molecular Films for Highly Selective CO₂ to CO Reduction

Thevenon, Arnaud and Rosas-Hernández, Alonso and Fontani-Herreros, Alex M. and Agapie, Theodor and Peters, Jonas C. (2021) Dramatic HER Suppression on Ag Electrodes via Molecular Films for Highly Selective CO₂ to CO Reduction. ACS Catalysis, 11 (8). pp. 4530-4537. ISSN 2155-5435. doi:10.1021/acscatal.1c00338.

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The carbon dioxide reduction reaction (CO₂RR) in aqueous electrolytes suffers from efficiency loss due to the competitive hydrogen evolution reaction (HER). Developing efficient methods to suppress HER is a crucial step toward CO₂ utilization. Herein we report the selective conversion of CO₂ to CO on planar silver electrodes with Faradaic efficiencies >99% using simple pyridinium-based additives. Similar to our previous studies on copper electrodes, the additives form an organic film which alters CO₂RR selectivity. We report electrochemical kinetic and other mechanistic data to shed light on the role of these organic layers in suppressing HER. These data suggest that hydrogen production is selectively inhibited by the growth of a hydrophobic organic layer on the silver surface that limits proton but not CO₂ mass transport at certain applied potentials. The data also point to the involvement of a proton-transfer within the rate-determining step of the catalysis, instead of the commonly observed electron-transfer step for the case of planar Ag electrodes.

Item Type:Article
Related URLs:
URLURL TypeDescription
Thevenon, Arnaud0000-0002-5543-6595
Rosas-Hernández, Alonso0000-0002-0812-5591
Agapie, Theodor0000-0002-9692-7614
Peters, Jonas C.0000-0002-6610-4414
Alternate Title:Dramatic HER Suppression on Ag Electrodes via Molecular Films for Highly Selective CO2 to CO Reduction
Additional Information:© 2021 American Chemical Society. Received: January 24, 2021; Revised: March 13, 2021; Published: March 29, 2021. NMR, AFM, and XPS, SEM, and EDX measurements were collected at the NMR Facility (Division of Chemistry and Chemical Engineering), the Molecular Materials Research Center (Beckman Institute), and the Analytic Facilities (Division of Geological and Planetary Sciences) of the California Institute of Technology, respectively. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under award number DE-SC0004993. A.T. acknowledges Marie Skłodowska-Curie Fellowship H2020-MSCA-IF-2017 (793471). J.C.P also acknowledges additional support from the Resnick Sustainability Institute at Caltech. The authors declare no competing financial interest.
Group:JCAP, Resnick Sustainability Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Marie Curie Fellowship793471
Resnick Sustainability InstituteUNSPECIFIED
Subject Keywords:electrocatalysis, CO₂RR, HER, solar fuels, modified electrodes, silver electrodes
Issue or Number:8
Record Number:CaltechAUTHORS:20210330-144253307
Persistent URL:
Official Citation:Dramatic HER Suppression on Ag Electrodes via Molecular Films for Highly Selective CO2 to CO Reduction. Arnaud Thevenon, Alonso Rosas-Hernández, Alex M. Fontani Herreros, Theodor Agapie, and Jonas C. Peters. ACS Catalysis 2021 11 (8), 4530-4537; DOI: 10.1021/acscatal.1c00338
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108586
Deposited By: Tony Diaz
Deposited On:30 Mar 2021 22:23
Last Modified:13 Aug 2021 16:25

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