open access

https://hdl.handle.net/2115/93926

Platinum–Nickel Alloy Nanowire Electrocatalysts Transform into Pt-Skin Beads-on-Nanowires Keeping Oxygen Reduction Reaction Activity During Potential Cycling

英語

spectroscopy

2024-01-18

ACS Catalysis

14(3)

1750-1758

We synthesized PtNi alloy nanowires (PtNi NWs) at three different temperatures of 433, 494, and 533 K (NW433 K, NW494 K, and NW533 K, respectively) and then investigated their catalytic activity and durability for the oxygen reduction reaction (ORR) in acidic media. Ni contents in the PtNi NWs increase as the synthesis temperatures increase from below 5 at. % for NW433 K up to about 15 at. % for NW493 K and NW553 K. PtNi nanoparticles (PtNi NPs), which are the unconsumed intermediate during the NW growth, also coexist for NW433 K and NW494 K but not for NW533 K. NW494 K and NW533 K show similar initial activity for the ORR but higher than NW433 K, suggesting that higher Ni contents are critical to achieving higher initial ORR activity. Accelerated durability tests (ADTs) show that NW493 K is the most durable, suggesting that the copresence of PtNi NPs is critical to durability. Only NW493 K, with a high Ni content of 15 at. % and coexisting PtNi NPs, gave better results in both cases. Scanning transmission electron microscopy and energy dispersive X-ray spectroscopy of PtNi NWs reveal a structural transformation of NW493 K into Pt-skin beads-on-nanowires, involving the Ostwald ripening of coexisting PtNi NPs. This structural transformation is coupled with changes in surface composition and surface electronic structure, as confirmed by the CO stripping voltammogram and in situ X-ray absorption spectroscopy, resulting in high durability and suppression of Pt and Ni dissolution. Understanding such structural transformation during potential cycling will help us to design and develop highly active and durable Pt-based electrocatalysts.

学術雑誌論文

Accepted Manuscript

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/articlesonrequest/AOR-IKVT8TII4IE2UQBFCNEE.

2155-5435