Biomimicking vitamin B12. A Co phthalocyanine pyridine axial ligand coordinated catalyst for the oxygen reduction reaction

Jorge Riquelme, Karinna Neira, José F. Marco, Patricio Hermosilla-Ibáñez, Walter Orellana, José H. Zagal, Federico Tasca

Resultado de la investigación: Article

9 Citas (Scopus)

Resumen

CoN4 complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR) but they only promote the 2-electron reduction of O2 to give peroxide. In contrast, vitamin B12 a Co macrocyclic naturally occurring molecule has attracted the attention of the scientific community because instead of catalysing the 2-electron reduction of O2 to H2O2 like the other Co macrocycles it promotes the 4-electron reduction to H2O. Vitamin B12 possesses an axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-electron reduction of O2. To test this hypothesis, we synthetized a CoPc axially coordinated to pyridine anchored to carbon nano-tubes (CoPc-Py-CNT). The Co centre is therefore coordinated to 5 N as in vitamin B12. The modified CoPc containing catalytic material was characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky– Levich extrapolation and Tafel plots well describe the similarities between the 2 complexes and reveal insights into the mechanism of action of Co penta-coordinated complexes. According to our results the pyridine back ligand increases the Co-O2 binding energy and making it more similar to that of Vitamin B12, favouring 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.

Idioma originalEnglish
Páginas (desde-hasta)547-555
Número de páginas9
PublicaciónElectrochimica Acta
Volumen265
DOI
EstadoPublished - 1 mar 2018

Huella dactilar

Vitamins
Vitamin B 12
Pyridine
Ligands
Oxygen
Catalysts
Electrons
Binding energy
Electrocatalysts
Peroxides
Extrapolation
Paramagnetic resonance
Carbon
X ray photoelectron spectroscopy
pyridine
phthalocyanine
Spectroscopy
Molecules

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Citar esto

Riquelme, Jorge ; Neira, Karinna ; Marco, José F. ; Hermosilla-Ibáñez, Patricio ; Orellana, Walter ; Zagal, José H. ; Tasca, Federico. / Biomimicking vitamin B12. A Co phthalocyanine pyridine axial ligand coordinated catalyst for the oxygen reduction reaction. En: Electrochimica Acta. 2018 ; Vol. 265. pp. 547-555.
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title = "Biomimicking vitamin B12. A Co phthalocyanine pyridine axial ligand coordinated catalyst for the oxygen reduction reaction",
abstract = "CoN4 complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR) but they only promote the 2-electron reduction of O2 to give peroxide. In contrast, vitamin B12 a Co macrocyclic naturally occurring molecule has attracted the attention of the scientific community because instead of catalysing the 2-electron reduction of O2 to H2O2 like the other Co macrocycles it promotes the 4-electron reduction to H2O. Vitamin B12 possesses an axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-electron reduction of O2. To test this hypothesis, we synthetized a CoPc axially coordinated to pyridine anchored to carbon nano-tubes (CoPc-Py-CNT). The Co centre is therefore coordinated to 5 N as in vitamin B12. The modified CoPc containing catalytic material was characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky– Levich extrapolation and Tafel plots well describe the similarities between the 2 complexes and reveal insights into the mechanism of action of Co penta-coordinated complexes. According to our results the pyridine back ligand increases the Co-O2 binding energy and making it more similar to that of Vitamin B12, favouring 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.",
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Biomimicking vitamin B12. A Co phthalocyanine pyridine axial ligand coordinated catalyst for the oxygen reduction reaction. / Riquelme, Jorge; Neira, Karinna; Marco, José F.; Hermosilla-Ibáñez, Patricio; Orellana, Walter; Zagal, José H.; Tasca, Federico.

En: Electrochimica Acta, Vol. 265, 01.03.2018, p. 547-555.

Resultado de la investigación: Article

TY - JOUR

T1 - Biomimicking vitamin B12. A Co phthalocyanine pyridine axial ligand coordinated catalyst for the oxygen reduction reaction

AU - Riquelme, Jorge

AU - Neira, Karinna

AU - Marco, José F.

AU - Hermosilla-Ibáñez, Patricio

AU - Orellana, Walter

AU - Zagal, José H.

AU - Tasca, Federico

PY - 2018/3/1

Y1 - 2018/3/1

N2 - CoN4 complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR) but they only promote the 2-electron reduction of O2 to give peroxide. In contrast, vitamin B12 a Co macrocyclic naturally occurring molecule has attracted the attention of the scientific community because instead of catalysing the 2-electron reduction of O2 to H2O2 like the other Co macrocycles it promotes the 4-electron reduction to H2O. Vitamin B12 possesses an axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-electron reduction of O2. To test this hypothesis, we synthetized a CoPc axially coordinated to pyridine anchored to carbon nano-tubes (CoPc-Py-CNT). The Co centre is therefore coordinated to 5 N as in vitamin B12. The modified CoPc containing catalytic material was characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky– Levich extrapolation and Tafel plots well describe the similarities between the 2 complexes and reveal insights into the mechanism of action of Co penta-coordinated complexes. According to our results the pyridine back ligand increases the Co-O2 binding energy and making it more similar to that of Vitamin B12, favouring 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.

AB - CoN4 complexes like Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR) but they only promote the 2-electron reduction of O2 to give peroxide. In contrast, vitamin B12 a Co macrocyclic naturally occurring molecule has attracted the attention of the scientific community because instead of catalysing the 2-electron reduction of O2 to H2O2 like the other Co macrocycles it promotes the 4-electron reduction to H2O. Vitamin B12 possesses an axial back ligand and this seems to be the reason for its higher activity and selectivity for the 4-electron reduction of O2. To test this hypothesis, we synthetized a CoPc axially coordinated to pyridine anchored to carbon nano-tubes (CoPc-Py-CNT). The Co centre is therefore coordinated to 5 N as in vitamin B12. The modified CoPc containing catalytic material was characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky– Levich extrapolation and Tafel plots well describe the similarities between the 2 complexes and reveal insights into the mechanism of action of Co penta-coordinated complexes. According to our results the pyridine back ligand increases the Co-O2 binding energy and making it more similar to that of Vitamin B12, favouring 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.

KW - Co phthalocyanine

KW - Electrocatalysis

KW - Fuel cell cathode

KW - Oxygen reduction reaction

KW - Vitamin B12

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U2 - 10.1016/j.electacta.2018.01.177

DO - 10.1016/j.electacta.2018.01.177

M3 - Article

AN - SCOPUS:85041552087

VL - 265

SP - 547

EP - 555

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

ER -