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One step synthesis of carbon-supported Ag/MnyOx composites for oxygen reduction reaction in alkaline media

Paper ID Volume ID Publish Year Pages File Format Full-Text
46972 46454 2011 9 PDF Available
Title
One step synthesis of carbon-supported Ag/MnyOx composites for oxygen reduction reaction in alkaline media
Abstract

Carbon-supported Ag/MnyOx composites were prepared by a one step synthesis method, i.e., silver permanganate pyrolysis at different temperatures. The physical and electrochemical properties of the obtained composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV). The electrochemical activity, selectivity and stability for the Ag/MnyOx/C composites toward oxygen reduction reaction (ORR) in alkaline media were investigated by rotating (ring)-disk electrode (R(R)DE) technique. The XRD results show that the manganese oxides were converted from MnO2 to Mn3O4 and then to MnO gradually with increasing temperature. Among all the Ag/MnyOx/C composites, Ag/Mn3O4/C obtained at 400 °C exhibits the highest activity toward the ORR. Compared with the Ag/C, Mn3O4/C and the physical mixture of Ag/C and Mn3O4/C with the same metal loadings, the ORR activity of the Ag/Mn3O4/C is improved significantly, suggesting a synergic effect between Ag and Mn3O4. At an overpotential of 0.35 V, the calculated apparent activation energy for the ORR on the Ag/Mn3O4/C catalyst is 56 kJ mol−1, which is apparently higher than that on a Pt/C catalyst (36 kJ mol−1). The results from both Koutecky–Levich plots of the ORR and the RRDE measurements suggest that the ORR proceeds via a 4-electron pathway on the Ag/Mn3O4/C composite. Moreover, the presence of methanol has little influence on the ORR activity toward the Ag/Mn3O4/C catalyst. The accelerated aging tests indicate that the Ag/Mn3O4/C is more stable than the Pt/C in 0.1 M NaOH solution.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Ag/MnyOx/C composites were synthesized by one-step pyrolysis of AgMnO4. ► The Ag/Mn3O4/C obtained at 400 °C is most active toward the ORR in alkaline media. ► A synergic effect between Ag and Mn3O4 is proposed. ► The ORR proceeds via a 4e− pathway on the Ag/Mn3O4/C. ► The Ag/Mn3O4/C is more stable than Pt/C in alkaline media.

Keywords
Oxygen reduction reaction; Alkaline media; Manganese oxide; Silver; One step synthesis
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One step synthesis of carbon-supported Ag/MnyOx composites for oxygen reduction reaction in alkaline media
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 104, Issues 3–4, 18 May 2011, Pages 337–345
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us