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  • Atomic-Scale Visualization of Surface Segregation and Ordering of Pt in a Dilute Cu(Pt) Alloy under a Hydrogen Atmosphere

This content will become publicly available on October 31, 2025

Title: Atomic-Scale Visualization of Surface Segregation and Ordering of Pt in a Dilute Cu(Pt) Alloy under a Hydrogen Atmosphere
Surface segregation is a common phenomenon in alloys exposed to reactive atmospheres, yet the atomic mechanisms underlying surface structure and composition dynamics remains largely unexplored. Using a combination of environmental transmission electron microscopy observations and atomistic modeling, here we report the surface segregation process of Pt atoms in a dilute Pt(Cu) alloy and determine the distribution of Pt atoms at both atomically flat and stepped surfaces of the Pt(Cu) alloy at elevated temperature and in a hydrogen gas atmosphere. Through directly probing Pt segregation, we find that Pt atoms segregated on the (100) surface exhibit a p(2×2) ordering, with ~25% Pt occupancy. In contrast, on the stepped (410) surface, hydrogen adsorption induces Pt segregation, initially occurring at the step edges, which then expands to the terrace sites upon increased hydrogen coverage, resulting in an ordered distribution of segregated Pt atoms with ~22% occupancy. These observations offer mechanistic insights into the structure and composition dynamics of the topmost atomic layer of the alloy in response to environmental stimuli and hold practical implications for the design and optimization of catalysts based on Pt group metals.  more » « less
Award ID(s):
1905422
PAR ID:
10554150
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
American Chemical Society
Date Published:
Journal Name:
The Journal of Physical Chemistry C
Volume:
128
Issue:
43
ISSN:
1932-7447
Page Range / eLocation ID:
18236 to 18246
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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