Climbing over the activity volcano correlation by biomimicking Vitamin B12: A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen

Jorge Riquelme, Karinna Neira, José F. Marco, Patricio Hcrmosilla, Diego Vencgas, Walter Orellana, Ingrid Ponce, José H. Zagal, Federico Tasca

Resultado de la investigación: Contribución a los tipos de informe/libroContribución a la conferencia

2 Citas (Scopus)

Resumen

CoN4 macrocyclic complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the ORR but they preferentially promote the 2-e reduction of O2 to give peroxide. In contrast, Vitamin B12, a naturally occurring CoN4 macrocyclic molecule alkaline media promotes the 4-electron reduction of O2 to H2O. Vitamin B12 possesses an imidazole axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-e reduction of O2. To test this hypothesis, we synthesized a CoPc axially coordinated to pyridine anchored to carbon nanotubes (Co-Py-CNT). The Co center is therefore coordinated to 5 nitrogens as in Vitamin B12. The modified CoPcPy containing catalytic material was characterized by EPR and XPS spectroscopy. DFT calculations. According to our results the pyridine back ligand increases the Co-O2 binding energy, making it more similar to VitB12, favoring the splitting of the O-O bond. The back ligand then plays a crucial role in modifying Co-O2 binding energy which is a well know reactivity descriptor. A further evidence of this dramatic change in reactivity of CoPc by the presence of the "Py" back ligand is that it moves from the weak binding leg of a volcano correlation to the strong leg of the volcano. This might explain why nature uses a back ligand in cytochrome c to catalyze the ORR.

Idioma originalInglés
Título de la publicación alojadaECS Transactions
EditorialElectrochemical Society, Inc.
Páginas111-121
Número de páginas11
Volumen85
Edición12
ISBN (versión digital)9781607685395
DOI
EstadoPublicada - 1 ene 2018
EventoElectrocatalysis 9: Symposium in Honor of Radoslav Adzic - 233rd ECS Meeting - Seattle, Estados Unidos
Duración: 13 may 201817 may 2018

Conferencia

ConferenciaElectrocatalysis 9: Symposium in Honor of Radoslav Adzic - 233rd ECS Meeting
PaísEstados Unidos
CiudadSeattle
Período13/05/1817/05/18

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    Riquelme, J., Neira, K., Marco, J. F., Hcrmosilla, P., Vencgas, D., Orellana, W., Ponce, I., Zagal, J. H., & Tasca, F. (2018). Climbing over the activity volcano correlation by biomimicking Vitamin B12: A co phthalocyanine pyridine axial ligand coordinated catalyst for the reduction of molecular oxygen. En ECS Transactions (12 ed., Vol. 85, pp. 111-121). Electrochemical Society, Inc.. https://doi.org/10.1149/08512.01ecst