Tuning the Activity of Heterogeneous Cofacial Cobalt Porphyrins for Oxygen Reduction Electrocatalysis through Self-Assembly

Amanda N Oldacre; Matthew R Crawley; Alan E Friedman; Timothy R Cook

doi:10.1002/chem.201802585

Tuning the Activity of Heterogeneous Cofacial Cobalt Porphyrins for Oxygen Reduction Electrocatalysis through Self-Assembly

Chemistry. 2018 Aug 1;24(43):10984-10987. doi: 10.1002/chem.201802585. Epub 2018 Jul 3.

Authors

Amanda N Oldacre¹, Matthew R Crawley¹, Alan E Friedman², Timothy R Cook¹

Affiliations

¹ Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.
² Department of Materials, Design, and Innovation, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA.

PMID: 29845658
DOI: 10.1002/chem.201802585

Abstract

We report a suite of coordination-driven self-assembled prisms for heterogeneous electrocatalytic oxygen reduction (ORR) differing in the molecular clips linking two porphyrin faces in a cofacial arrangement. ORR activities and selectivities of monomeric CoTPyP along with cofacial prisms Ox-Co, Oxa-Co, and Benzo-Co were probed using cyclic voltammetry and rotating ring-disk techniques. All species were immobilized as heterogeneous catalysts on glassy carbon electrodes using a Nafion ink method. The selectivities of Ox-Co, Oxa-Co, and Benzo-Co prisms towards H₂ O as determined by RRDE were 87, 97, and 75 %, respectively. The current density of the Oxa-Co plateaus at five times that of Pt/C when normalized per Co/Pt. The high synthetic yield (79 %), competitive overpotential (η ≈800 mV) and high selectivity (%H₂ O ≈97 %) of the Oxa-Co highlights how self-assembly can be used to address multi-electron multi-proton transformations using polynuclear catalysts.

Keywords: catalysis; heterogeneous; oxygen reduction; porphyrin; self-assembly.