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As the development of polymer electrolyte membrane fuel cells (PEMFCs) has sped up in recent years, producing active and durable electrocatalysts has become an increasingly important technical challenge. Platinum–cobalt (Pt–Co) alloy electrocatalyst has been commercially applied to hydrogen-powered fuel cell vehicles, and their intermetallic forms promise better durability, which is crucial to satisfy the 8000 h lifetime target of heavy-duty vehicles and other transportation options. In this feature article, we first present the atomically ordered structures of Pt–Co intermetallic, then discuss the thermodynamic and kinetic driving forces for making the PtCo-based intermetallic nanoparticles with desired structural attributes, followed by recent examples to illustrate how to achieve better control in composition, size, and shape. Discussion on the relationship between the key structural features and catalytic performance is focused on the application of Pt–Co intermetallic nanostructures as oxygen reduction reaction (ORR) electrocatalysts for hydrogen-powered PEMFCs. We emphasize specifically the importance of intermetallic structures for enhancing the durability and summarize the characterizations of their electrocatalytic performance in both three-electrode system and full cell studies. Finally, we provide our perspectives on the design, synthesis, characterization, and property studies of Pt–Co intermetallic nanoparticles as ORR electrocatalysts. This article should provide a new understanding on the design of ORR electrocatalytic applications using this class of intermetallics.
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Electric Field Poling Effect on the Electrocatalytic Properties of Nitrogen-Functionalized Graphene Nanosheets
Fuel cells are attractive new technologies for producing sustainable and green energy. However, the high cost of its components such as Pt electrocatalyst is a major challenge. Heteroatom doped carbon nano‐materials show potential applications for oxygen reduction reaction (ORR) which can be used for fuel cells and may be promising replacement of Pt catalyst. Recently, we implemented a facile method for preparing partially nitrogen functionalized graphene oxide (PNG) nano‐sheets. To achieve better nitrogen functionalization, graphene oxide was annealed in ammonia solution for 12 h at 220oC. The electrochemical measurement data show that the PNG synthesized in NH3 environment possesses good electrocatalytic activities for ORR. In addition, we identified a physical method for the first time to drive the randomly oriented graphene nano‐sheets to be aligned parallel to the surface of electrode for electrocatalytic application by using an AC electric field. An additional effect of the applied electric field is the induction of a polarization on PNG nano‐sheets that create a dielectrophoresis phenomenon. The poling effect of the electric field on the sample shows much improved electrocatalytic performance. The enhanced catalysis can be used for ORR as an important reaction in fuel cells. The reported new method can achieve a low cost capability for preparing new electrocatalyst electrodes for large‐scale applications.
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- Award ID(s):
- 1736136
- PAR ID:
- 10072732
- Date Published:
- Journal Name:
- Energy Technology
- ISSN:
- 2194-4288
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/ente.201800327
