Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction
The oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co<sub>3</su...
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MDPI AG
2021-04-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/11/4/925 |
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| author | Loukas Belles Constantinos Moularas Szymon Smykała Yiannis Deligiannakis |
| author_facet | Loukas Belles Constantinos Moularas Szymon Smykała Yiannis Deligiannakis |
| author_sort | Loukas Belles |
| collection | DOAJ |
| description | The oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co<sub>3</sub>O<sub>4</sub> and CoO/Co<sub>3</sub>O<sub>4</sub> nanostructures using flame spray pyrolysis (FSP), as electrocatalysts for ORR in acidic and alkaline media. A detailed study of the effect of (Co-oxide)/Pt ratio on ORR efficiency shows that the present FSP-made Co-oxides are able to perform ORR at very low-Pt loading, 0.4% of total metal content. In acid medium, an electrode with (5.2% Pt + 4.8% Co<sub>3</sub>O<sub>4</sub>), achieved the highest ORR performance (J<sub>max</sub> = 8.31 mA/cm<sup>2</sup>, E<sub>1/2</sub> = 0.66 V). In alkaline medium, superior performance and stability have been achieved by an electrode with (0.4%Pt + 9.6% (CoO/Co<sub>3</sub>O<sub>4</sub>)) with ORR activity (J<sub>max</sub> = 3.5 mA/cm<sup>2</sup>, E<sub>1/2</sub> = 0.08 V). Using XRD, XPS, Raman and TEM data, we discuss the structural and electronic aspects of the FSP-made Co-oxide catalysts in relation to the ORR performance. Cyclic voltammetry data indicate that the ORR process involves active sites associated with Co<sup>3+</sup> cations at the cobalt oxide surface. Technology-wise, the present work demonstrates that the developed FSP-protocols, constitutes a novel scalable process for production of co-oxides appropriate for oxygen reduction reaction electrodes. |
| first_indexed | 2024-03-10T12:35:43Z |
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| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-10T12:35:43Z |
| publishDate | 2021-04-01 |
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| series | Nanomaterials |
| spelling | doaj.art-645c274001f949c98afd06d1426314322023-11-21T14:16:16ZengMDPI AGNanomaterials2079-49912021-04-0111492510.3390/nano11040925Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction ReactionLoukas Belles0Constantinos Moularas1Szymon Smykała2Yiannis Deligiannakis3Laboratory of Physics Chemistry of Materials & Environment, Department of Physics, University of Ioannina, 45550 Ioannina, GreeceLaboratory of Physics Chemistry of Materials & Environment, Department of Physics, University of Ioannina, 45550 Ioannina, GreeceInstitute of Engineering Materials and Biomaterials, Silesian University of Technology, 18a Konarskiego St, 44-100 Gliwice, PolandLaboratory of Physics Chemistry of Materials & Environment, Department of Physics, University of Ioannina, 45550 Ioannina, GreeceThe oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co<sub>3</sub>O<sub>4</sub> and CoO/Co<sub>3</sub>O<sub>4</sub> nanostructures using flame spray pyrolysis (FSP), as electrocatalysts for ORR in acidic and alkaline media. A detailed study of the effect of (Co-oxide)/Pt ratio on ORR efficiency shows that the present FSP-made Co-oxides are able to perform ORR at very low-Pt loading, 0.4% of total metal content. In acid medium, an electrode with (5.2% Pt + 4.8% Co<sub>3</sub>O<sub>4</sub>), achieved the highest ORR performance (J<sub>max</sub> = 8.31 mA/cm<sup>2</sup>, E<sub>1/2</sub> = 0.66 V). In alkaline medium, superior performance and stability have been achieved by an electrode with (0.4%Pt + 9.6% (CoO/Co<sub>3</sub>O<sub>4</sub>)) with ORR activity (J<sub>max</sub> = 3.5 mA/cm<sup>2</sup>, E<sub>1/2</sub> = 0.08 V). Using XRD, XPS, Raman and TEM data, we discuss the structural and electronic aspects of the FSP-made Co-oxide catalysts in relation to the ORR performance. Cyclic voltammetry data indicate that the ORR process involves active sites associated with Co<sup>3+</sup> cations at the cobalt oxide surface. Technology-wise, the present work demonstrates that the developed FSP-protocols, constitutes a novel scalable process for production of co-oxides appropriate for oxygen reduction reaction electrodes.https://www.mdpi.com/2079-4991/11/4/925Oxygen Reduction Reaction (ORR)Flame Spray Pyrolysis (FSP)cobalt oxidenanomaterialsfuel cellsrotating disc electrode (RDE) |
| spellingShingle | Loukas Belles Constantinos Moularas Szymon Smykała Yiannis Deligiannakis Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction Nanomaterials Oxygen Reduction Reaction (ORR) Flame Spray Pyrolysis (FSP) cobalt oxide nanomaterials fuel cells rotating disc electrode (RDE) |
| title | Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction |
| title_full | Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction |
| title_fullStr | Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction |
| title_full_unstemmed | Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction |
| title_short | Flame Spray Pyrolysis Co<sub>3</sub>O<sub>4</sub>/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction |
| title_sort | flame spray pyrolysis co sub 3 sub o sub 4 sub coo as highly efficient nanocatalyst for oxygen reduction reaction |
| topic | Oxygen Reduction Reaction (ORR) Flame Spray Pyrolysis (FSP) cobalt oxide nanomaterials fuel cells rotating disc electrode (RDE) |
| url | https://www.mdpi.com/2079-4991/11/4/925 |
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