Modulating the mechanism of electrocatalytic CO2 reduction by cobalt phthalocyanine through polymer coordination and encapsulation

• Published in: Nature communications Vol. 10; no. 1; p. 1683
• Main Authors: Liu, Yingshuo, McCrory, Charles C. L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 11.04.2019; Nature Publishing Group UK; Nature Portfolio
• Subjects: Business competition; Carbon dioxide; Catalysis; Catalysts; Chemical reduction; Cobalt; Composite materials; Coordination polymers; Electrocatalysts; Electrochemistry; Encapsulation; Hydrogen evolution; Isotope effect; Polymer matrix composites; Polymers; Protons; Selectivity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09626-8

Abstract The selective and efficient electrochemical reduction of CO 2 to single products is crucial for solar fuels development. Encapsulating molecular catalysts such as cobalt phthalocyanine within coordination polymers such as poly-4-vinylpyridine leads to dramatically increased activity and selectivity for CO 2 reduction. In this study, we use a combination of kinetic isotope effect and proton inventory studies to explain the observed increase in activity and selectivity upon polymer encapsulation. We provide evidence that axial-coordination from the pyridyl moieties in poly-4-vinylpyridine to the cobalt phthalocyanine complex changes the rate-determining step in the CO 2 reduction mechanism accounting for the increased activity in the catalyst-polymer composite. Moreover, we show that proton delivery to cobalt centers within the polymer is controlled by a proton relay mechanism that inhibits competitive hydrogen evolution. These mechanistic findings provide design strategies for selective CO 2 reduction electrocatalysts and serve as a model for understanding the catalytic mechanism of related heterogeneous systems.