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Intensified Electrocatalytic CO 2 Conversion in Pressure‐Tunable CO 2 ‐Expanded Electrolytes
Author(s) -
Shaughnessy Charles I.,
Sconyers David J.,
Kerr Tyler A.,
Lee HyunJin,
Subramaniam Bala,
Leonard Kevin C.,
Blakemore James D.
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201901107
Subject(s) - electrolyte , catalysis , ambient pressure , dissolution , chemistry , selectivity , polarization (electrochemistry) , inorganic chemistry , chemical engineering , electrocatalyst , electrochemistry , electrode , materials science , organic chemistry , thermodynamics , physics , engineering
Multimolar CO 2 concentrations are achieved in acetonitrile solutions containing supporting electrolyte at relatively mild CO 2 pressures (<5 MPa) and ambient temperature. Such CO 2 ‐rich, electrolyte‐containing solutions are termed as C O 2 ‐e X panded E lectrolytes (CXEs) because significant volumetric expansion of the liquid phase accompanies CO 2 dissolution. Cathodic polarization of a model polycrystalline gold electrode‐catalyst in CXE media enhances CO 2 to CO conversion rates by up to an order of magnitude compared with those attainable at near‐ambient pressures, without loss of selectivity. The observed catalytic process intensification stems primarily from markedly increased CO 2 availability. However, a non‐monotonic correlation between the dissolved CO 2 concentration and catalytic activity is observed, with an optimum occurring at approximately 5 m CO 2 concentration. At the highest applied CO 2 pressures, catalysis is significantly attenuated despite higher CO 2 concentrations and improved mass‐transport characteristics, attributed in part to increased solution resistance. These results reveal that pressure‐tunable CXE media can significantly intensify CO 2 reduction rates over known electrocatalysts by alleviating substrate starvation, with CO 2 pressure as a crucial variable for optimizing the efficiency of electrocatalytic CO 2 conversion.