Volume 26, Issue 70 p. 16774-16781
Full Paper

Enhanced Electrocatalytic Activity of a Zinc Porphyrin for CO2 Reduction: Cooperative Effects of Triazole Units in the Second Coordination Sphere

Amir Lashgari

Amir Lashgari

Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH, 45221 United States

These authors contributed equally to this work.

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Caroline K. Williams

Caroline K. Williams

Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH, 45221 United States

These authors contributed equally to this work.

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Jenna L. Glover

Jenna L. Glover

Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH, 45221 United States

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Yueshen Wu

Yueshen Wu

Department of Chemistry, Yale University, New Haven, Connecticut, 06520 United States

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Dr. Jingchao Chai

Dr. Jingchao Chai

Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH, 45221 United States

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Prof. Jianbing “Jimmy” Jiang

Corresponding Author

Prof. Jianbing “Jimmy” Jiang

Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH, 45221 United States

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First published: 23 July 2020
Citations: 19

Graphical Abstract

A set of zinc porphyrin electrocatalysts with flexible triazole units as the second coordination spheres is prepared for cooperative-effect studies. The electrocatalyst with a triazole bundle displays efficient CO2-to-CO conversion with a Faradaic efficiency of 99 % and a current density of −6.2 mA cm−2 at −2.4 V vs. Fc/Fc+.

Abstract

The control of the second coordination sphere in a coordination complex plays an important role in improving catalytic efficiency. Herein, we report a zinc porphyrin complex ZnPor8T with multiple flexible triazole units comprising the second coordination sphere, as an electrocatalyst for the highly selective electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO). This electrocatalyst converted CO2 to CO with a Faradaic efficiency of 99 % and a current density of −6.2 mA cm−2 at −2.4 V vs. Fc/Fc+ in N,N-dimethylformamide using water as the proton source. Structure-function relationship studies were carried out on ZnPor8T analogs containing different numbers of triazole units and distinct triazole geometries; these unveiled that the triazole units function cooperatively to stabilize the CO2-catalyst adduct in order to facilitate intramolecular proton transfer. Our findings demonstrate that incorporating triazole units that function in a cooperative manner is a versatile strategy to enhance the activity of electrocatalytic CO2 conversion.

Conflict of interest

The authors declare no conflict of interest.