Understanding the effects of anion interactions with Ag electrodes on electrochemical CO2 reduction in choline halide electrolytes

Garg, Sahil and Li, Mengran and Wu, Yuming and Idros, Mohamed Nazmi and Wang, Hongmin and Yago, Anya Josefa and Ge, Lei ORCID: https://orcid.org/0000-0003-2989-0329 and Wang, Geoff G. X. and Rufford, Thomas E. (2021) Understanding the effects of anion interactions with Ag electrodes on electrochemical CO2 reduction in choline halide electrolytes. ChemSusChem, 14 (12). pp. 2601-2611. ISSN 1864-5631


Abstract

Interactions of electrolyte ions at electrocatalyst surfaces influence the selectivity of electrochemical CO2 reduction (CO2R) to chemical feedstocks like CO. We investigated the effects of anion type in aqueous choline halide solutions (ChCl, ChBr, and ChI) on the selectivity of CO2R to CO over an Ag foil cathode. Using an H-type cell, we observed that halide-specific adsorption at the Ag surface limits CO faradaic efficiency (FECO) at potentials more positive than −1.0 V vs. reversible hydrogen electrode (RHE). At these conditions, FECO increased from I−−−, that is, in the opposite order to the strength of specific adsorption of the halide ions (Cl−−−). At potentials of −1.0 to −1.3 V vs. RHE, restructuring of the Ag surface in ChI and ChCl via dissolution and re-electrodeposition led to more CO-selective Ag facets ([220], [311], and [222]) than in ChBr. This mechanism allowed very high faradaic efficiencies for CO of 97±2 % in ChI and 94±2 % in ChCl to be achieved simultaneously with high current densities at −1.3 V vs. RHE. We also demonstrate that high selectivity to CO (FECO>90 %) in ChCl (at −0.75±0.06 Vvs. RHE) and ChI (at −0.78±0.17 V vs. RHE) could be achieved at a current density of 150 mA cm−2 in a continuous flow-cell electrolyser with Ag nanoparticles on a commercial gas diffusion electrode. This study provides new insights to understand the interactions of anions with catalysts and offers a new method to modify electrocatalyst surfaces.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 29 Jun 2021 03:15
Last Modified: 26 Oct 2021 23:49
Uncontrolled Keywords: choline ions; electrochemical CO2 reduction; halides; restructuring; specific adsorption
Fields of Research (2008): 03 Chemical Sciences > 0303 Macromolecular and Materials Chemistry > 030301 Chemical Characterisation of Materials
09 Engineering > 0904 Chemical Engineering > 090402 Catalytic Process Engineering
Fields of Research (2020): 40 ENGINEERING > 4004 Chemical engineering > 400404 Electrochemical energy storage and conversion
Identification Number or DOI: https://doi.org/10.1002/cssc.202100848
URI: http://eprints.usq.edu.au/id/eprint/42472

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