Adsorbate-induced structural changes in 1-3 nm platinum nanoparticles.
Yu Lei1, Haiyan Zhao, Rosa Diaz Rivas
1Energy Systems Division, ‡X-ray Science Division, §Chemical Sciences and Engineering Division, Argonne National Laboratory , Lemont, Illinois 60439, United States.
Journal of the American Chemical Society
|June 13, 2014
Summary
Platinum nanoparticle structure changes with hydrogen and carbon monoxide adsorption. Adsorbates like H2 and CO influence platinum-platinum bond distance and crystallinity, impacting nanoparticle properties.
Area of Science:
- Materials Science
- Surface Science
- Nanotechnology
Background:
- Platinum nanoparticles exhibit unique properties influenced by their size and surface interactions.
- Understanding nanoparticle behavior under adsorbate exposure is crucial for catalysis and materials design.
Purpose of the Study:
- To investigate the impact of particle size and adsorbate type (H2, CO) on platinum nanoparticle structure.
- To elucidate the relationship between adsorbate interactions and changes in Pt-Pt bond distance, crystallinity, and coordination.
Main Methods:
- Synchrotron radiation pair distribution function (PDF) analysis.
- X-ray absorption spectroscopy (XAS), including in situ X-ray near-edge absorption structure (XANES) measurements.
Main Results:
- Platinum nanoparticles (∼1 nm) displayed a Pt-Pt bond distance contraction of ∼1.4%.
- Adsorption of H2 and CO at room temperature relaxed this contraction towards bulk values.
- H2 adsorption enhanced nanoparticle crystallinity, while CO adsorption induced a more disordered fcc structure due to electron back-donation.
Conclusions:
- Adsorbate interactions significantly modify the structural and electronic properties of small platinum nanoparticles.
- Electron back-donation from Pt to CO is a key factor in the observed structural disorder during CO adsorption.
