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Polymer coordination promotes selective CO_2 reduction by cobalt phthalocyanine

Kramer, W. W. and McCrory, C. C. L. (2016) Polymer coordination promotes selective CO_2 reduction by cobalt phthalocyanine. Chemical Science, 7 (4). pp. 2506-2515. ISSN 2041-6520. PMCID PMC5477023.

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Cobalt phthalocyanine (CoPc) is a known electrocatalyst for the carbon dioxide reduction reaction (CO_2RR) that, when adsorbed onto edge-plane graphite (EPG) electrodes, shows modest activity and selectivity for CO production along with co-generation of H_2. In contrast, electrodes modified with CoPc immobilized in a poly-4-vinylpridine (P4VP) film show dramatically enhanced activity and selectivity compared to those modified with CoPc alone. CoPc-P4VP films display a faradaic efficiency of ∼90% for CO, with a turnover frequency of 4.8 s^(−1) at just −0.75 V vs. RHE. Two properties of P4VP contribute to enhancing the activity of CoPc: (1) the ability of individual pyridine residues to coordinate to CoPc and (2) the high concentration of uncoordinated pyridine residues throughout the film which may enhance the catalytic activity of CoPc through secondary and other outer coordination sphere effects. Electrodes modified with polymer-free, five-coordinate CoPc(py) films (py = pyridine) and with CoPc catalysts immobilized in non-coordinating poly-2-vinylpyridine films were prepared to independently investigate the role that each property plays in enhancing CO_2RR performance of CoPc-P4VP. These studies show that a synergistic relationship between the primary and outer coordination sphere effects is responsible for the enhanced catalytic activity of CoPc when embedded in the P4VP membrane.

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McCrory, C. C. L.0000-0001-9039-7192
Alternate Title:Polymer coordination promotes selective CO2 reduction by cobalt phthalocyanine
Additional Information:© 2016 The Royal Society of Chemistry. This Open Access Article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Received 22nd October 2015. Accepted 1st February 2016. First published online 02 Feb 2016. Chem. Sci., 2016, Advance Article. We are very grateful to Professor Harry Gray and Dr Xenia Amashukeli for helpful discussions and enthusiastic input during the preparation of this manuscript. We acknowledge additional useful discussions with Dr Ivonne M. Ferrer regarding the initial acquisition and analysis of controlled-potential electrolysis data. This work was supported by the California Energy Commission Agreement 500-11-023 “Accelerating the Development of Liquid Fuels Directly from Sunlight”.
Group:CCI Solar Fuels
Funding AgencyGrant Number
California Energy Commission500-11-023
Issue or Number:4
PubMed Central ID:PMC5477023
Record Number:CaltechAUTHORS:20160222-115824828
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Official Citation:Polymer coordination promotes selective CO2 reduction by cobalt phthalocyanine W. W. Kramer and C. C. L. McCrory Chem. Sci., 2016,7, 2506-2515 DOI: 10.1039/C5SC04015A
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64634
Deposited By: Ruth Sustaita
Deposited On:22 Feb 2016 20:59
Last Modified:03 Oct 2019 09:39

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