Catalyst Aggregation Matters for Immobilized Molecular CO 2 RR Electrocatalysts

Here, we detail how the catalytic behavior of immobilized molecular electrocatalysts for the CO reduction reaction (CO RR) can be impacted by catalyst aggregation. Raman spectroscopy was used to study the CO RR mediated by a layer of cobalt phthalocyanine (CoPc) immobilized on the cathode of an elec...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2023-03, Vol.145 (8), p.4414-4420
Main Authors: Ren, Shaoxuan, Lees, Eric W, Hunt, Camden, Jewlal, Andrew, Kim, Yongwook, Zhang, Zishuai, Mowbray, Benjamin A W, Fink, Arthur G, Melo, Luke, Grant, Edward R, Berlinguette, Curtis P
Format: Article
Language:English
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Summary:Here, we detail how the catalytic behavior of immobilized molecular electrocatalysts for the CO reduction reaction (CO RR) can be impacted by catalyst aggregation. Raman spectroscopy was used to study the CO RR mediated by a layer of cobalt phthalocyanine (CoPc) immobilized on the cathode of an electrochemical flow reactor. We demonstrate that during electrolysis, the oxidation state of CoPc in the catalyst layer is dependent upon the degree of catalyst aggregation. Our data indicate that immobilized molecular catalysts must be dispersed on conductive supports to mitigate the formation of aggregates and produce meaningful performance data. We leveraged insights from this mechanistic study to engineer an improved CO-forming immobilized molecular catalyst─cobalt octaethoxyphthalocyanine (EtO -CoPc)─that exhibited high selectivity (FE ≥ 95%), high partial current density ( ≥ 300 mA/cm ), and high durability (ΔFE < 0.1%/h at 150 mA/cm ) in a flow cell. This work demonstrates how to accurately identify CO RR active species of molecular catalysts using Raman spectroscopy and how to use this information to implement improved molecular electrocatalysts into flow cells. This work also shows that the active site of CoPc during CO RR catalysis in a flow cell is the metal center.
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.2c08380