Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines
From the early 60s, Co complexes, especially Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR). Generally, they promote the 2-electron reduction of O2 to give peroxide whereas the 4-electron reduction is preferred for fuel cell applic...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2020-01-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fchem.2020.00022/full |
| _version_ | 1818325174409232384 |
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| author | Marco Viera Jorge Riquelme Carolina Aliaga José F. Marco Walter Orellana José H. Zagal Federico Tasca |
| author_facet | Marco Viera Jorge Riquelme Carolina Aliaga José F. Marco Walter Orellana José H. Zagal Federico Tasca |
| author_sort | Marco Viera |
| collection | DOAJ |
| description | From the early 60s, Co complexes, especially Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR). Generally, they promote the 2-electron reduction of O2 to give peroxide whereas the 4-electron reduction is preferred for fuel cell applications. Still, Co complexes are of interest because depending on the chemical environment of the Co metal centers either promote the 2-electron transfer process or the 4-electron transfer. In this study, we synthetized 3 different Co catalysts where Co is coordinated to 5 N atoms using CoN4 phthalocyanines with a pyridine axial linker anchored to carbon nanotubes. We tested complexes with electro-withdrawing or electro-donating residues on the N4 phthalocyanine ligand. The catalysts were characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky–Levich extrapolation and Tafel plots confirm that the pyridine back ligand increases the Co-O2 binding energy, and therefore promotes the 4-electron reduction of O2. But the presence of electron withdrawing residues, in the plane of the tetra N atoms coordinating the Co, does not further increase the activity of the compounds because of pull-push electronic effects. |
| first_indexed | 2024-12-13T11:40:17Z |
| format | Article |
| id | doaj.art-a1fb46ab644a45e5b2cc63b34317aa9e |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-12-13T11:40:17Z |
| publishDate | 2020-01-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Chemistry |
| spelling | doaj.art-a1fb46ab644a45e5b2cc63b34317aa9e2022-12-21T23:47:40ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462020-01-01810.3389/fchem.2020.00022507501Oxygen Reduction Reaction at Penta-Coordinated Co PhthalocyaninesMarco Viera0Jorge Riquelme1Carolina Aliaga2José F. Marco3Walter Orellana4José H. Zagal5Federico Tasca6Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, ChileDepartamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, ChileDepartamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, ChileInstituto de Química Física “Rocasolano”, CSIC, Madrid, SpainDepartamento de Ciencias Físicas, Universidad Andrés Bello, Santiago, ChileDepartamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, ChileDepartamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, ChileFrom the early 60s, Co complexes, especially Co phthalocyanines (CoPc) have been extensively studied as electrocatalysts for the oxygen reduction reaction (ORR). Generally, they promote the 2-electron reduction of O2 to give peroxide whereas the 4-electron reduction is preferred for fuel cell applications. Still, Co complexes are of interest because depending on the chemical environment of the Co metal centers either promote the 2-electron transfer process or the 4-electron transfer. In this study, we synthetized 3 different Co catalysts where Co is coordinated to 5 N atoms using CoN4 phthalocyanines with a pyridine axial linker anchored to carbon nanotubes. We tested complexes with electro-withdrawing or electro-donating residues on the N4 phthalocyanine ligand. The catalysts were characterized by EPR and XPS spectroscopy. Ab initio calculations, Koutecky–Levich extrapolation and Tafel plots confirm that the pyridine back ligand increases the Co-O2 binding energy, and therefore promotes the 4-electron reduction of O2. But the presence of electron withdrawing residues, in the plane of the tetra N atoms coordinating the Co, does not further increase the activity of the compounds because of pull-push electronic effects.https://www.frontiersin.org/article/10.3389/fchem.2020.00022/fullCo phthalocyaninepenta-coordinated Co phthalocyaninesoxygen reduction reactionelectrocatalysisvolcano correlations |
| spellingShingle | Marco Viera Jorge Riquelme Carolina Aliaga José F. Marco Walter Orellana José H. Zagal Federico Tasca Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines Frontiers in Chemistry Co phthalocyanine penta-coordinated Co phthalocyanines oxygen reduction reaction electrocatalysis volcano correlations |
| title | Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines |
| title_full | Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines |
| title_fullStr | Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines |
| title_full_unstemmed | Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines |
| title_short | Oxygen Reduction Reaction at Penta-Coordinated Co Phthalocyanines |
| title_sort | oxygen reduction reaction at penta coordinated co phthalocyanines |
| topic | Co phthalocyanine penta-coordinated Co phthalocyanines oxygen reduction reaction electrocatalysis volcano correlations |
| url | https://www.frontiersin.org/article/10.3389/fchem.2020.00022/full |
| work_keys_str_mv | AT marcoviera oxygenreductionreactionatpentacoordinatedcophthalocyanines AT jorgeriquelme oxygenreductionreactionatpentacoordinatedcophthalocyanines AT carolinaaliaga oxygenreductionreactionatpentacoordinatedcophthalocyanines AT josefmarco oxygenreductionreactionatpentacoordinatedcophthalocyanines AT walterorellana oxygenreductionreactionatpentacoordinatedcophthalocyanines AT josehzagal oxygenreductionreactionatpentacoordinatedcophthalocyanines AT federicotasca oxygenreductionreactionatpentacoordinatedcophthalocyanines |