Heterogenized Pyridine-Substituted Cobalt(II) Phthalocyanine Yields Reduction of CO2 by Tuning the Electron Affinity of the Co Center

Alberto De Riccardis; Michelle Lee; Roman V Kazantsev; Alejandro J Garza; Guosong Zeng; David M Larson; Ezra L Clark; Peter Lobaccaro; Paul W W Burroughs; Ermelinda Bloise; Joel W Ager; Alexis T Bell; Martin Head-Gordon; Giuseppe Mele; Francesca M Toma

doi:10.1021/acsami.9b18924

Heterogenized Pyridine-Substituted Cobalt(II) Phthalocyanine Yields Reduction of CO₂ by Tuning the Electron Affinity of the Co Center

ACS Appl Mater Interfaces. 2020 Feb 5;12(5):5251-5258. doi: 10.1021/acsami.9b18924. Epub 2020 Jan 23.

Affiliations

¹ Department of Engineering for Innovation , University of Salento , via Arnesano , Lecce 73100 , Italy.
² Department of Chemistry and Chemical Biology , Cornell University , Ithaca 14850 , New York , United States.
³ Department of Chemistry , University of California , Berkeley 94720 , California , United States.

PMID: 31971360
DOI: 10.1021/acsami.9b18924

Abstract

Conversion of CO₂ to reduced products is a promising route to alleviate irreversible climate change. Here we report the synthesis of a Co-based phthalocyanine with pyridine moieties (CoPc-Pyr), which is supported on a carbon electrode and shows Faradaic efficiency ∼90% for CO at 490 mV of overpotential (-0.6 V vs reversible hydrogen electrode (RHE)). In addition, its catalytic activity at -0.7 V versus RHE surpasses other Co-based molecular and metal-organic framework catalysts for CO₂ reduction at this bias. Density functional theory calculations show that pyridine moieties enhance CO₂ adsorption and electron affinity of the Co center by an inductive effect, thus lowering the overpotential necessary for CO₂ conversion. Our study shows that CoPc-Pyr reduces CO₂ at lower overpotential and with higher activity than noble metal electrodes, such as silver.

Keywords: CO2 electroreduction; electronic properties; heterogenized catalysis; molecular catalyst; phthalocyanine.