Engineering the crystal structure of Pt–M (M = transition metal) nanoalloys to chemically ordered ones has drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis due to their high resistance against M etching in acid. Although Pt–Ni alloy nanoparticles (NPs) have demonstrated respectable initial ORR activity in acid, their stability remains a big challenge due to the fast etching of Ni. In this work, sub‐6 nm monodisperse chemically ordered
One of the challenges in polymer electrolyte membrane fuel cells (PEMFCs) is developing cost‐effective, active and stable catalyst for oxygen reduction reaction (ORR). Platinum alloy‐based catalyst materials have drawn great attention and been intensively investigated for the excellent activity property, with some of them already exceeding 2020 DOE target for the ORR activity. In the meantime, the electrochemical stability of these Pt alloys remains a challenge to be overcome. This review first highlights important understandings of ORR pathways and mechanisms and then proceeds to summarize recent research progresses on development of Pt alloy catalyst materials. Current obstacles in Pt alloy catalyst research are discussed, with the stability issue being specifically emphasized and a theoretical model being developed for depicting the stability property. This review also provides perspectives of future research directions in this field.
more » « less- Award ID(s):
- 1665265
- NSF-PAR ID:
- 10117407
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemNanoMat
- Volume:
- 6
- Issue:
- 1
- ISSN:
- 2199-692X
- Page Range / eLocation ID:
- p. 32-41
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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null (Ed.)One of the key challenges that hinders broad commercialization of proton exchange membrane fuel cells is the high cost and inadequate performance of the catalysts for the oxygen reduction reaction (ORR). Here we report a composite ORR catalyst consisting of ordered intermetallic Pt-alloy nanoparticles attached to an N-doped carbon substrate with atomically dispersed Fe–N–C sites, demonstrating substantially enhanced catalytic activity and durability, achieving a half-wave potential of 0.923 V ( vs. RHE) and negligible activity loss after 5000 cycles of an accelerated durability test. The composite catalyst is prepared by deposition of Pt nanoparticles on an N-doped carbon substrate with atomically dispersed Fe–N–C sites derived from a metal–organic framework and subsequent thermal treatment. The latter results in the formation of core–shell structured Pt-alloy nanoparticles with ordered intermetallic Pt 3 M (M = Fe and Zn) as the core and Pt atoms on the shell surface, which is beneficial to both the ORR activity and stability. The presence of Fe in the porous Fe–N–C substrate not only provides more active sites for the ORR but also effectively enhances the durability of the composite catalyst. The observed enhancement in performance is attributed mainly to the unique structure of the composite catalyst, as confirmed by experimental measurements and computational analyses. Furthermore, a fuel cell constructed using the as-developed ORR catalyst demonstrates a peak power density of 1.31 W cm −2 . The strategy developed in this work is applicable to the development of composite catalysts for other electrocatalytic reactions.more » « less
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