Title
Kinetics, energetics, and size dependence of the transformation from Pt to ordered PtSn intermetallic nanoparticles
Publication Date
2-18-2019
Department
Ames Laboratory; Chemistry; Physics and Astronomy
Campus Units
Ames Laboratory, Chemistry, Physics and Astronomy
OSTI ID+
1498573
Report Number
IS-J 9927
DOI
10.1039/C8NR10067E
Journal Title
Nanoscale
Volume Number
11
Issue Number
12
First Page
5336
Last Page
5345
Abstract
The outstanding catalytic activity and chemical selectivity of intermetallic compounds make them excellent candidates for heterogeneous catalysis. However, the kinetics of their formation at the nanoscale is poorly understood or characterized, and precise control of their size, shape and composition during synthesis remains challenging. Here, using well-defined Pt nanoparticles (5 nm and 14 nm) encapsulated in mesoporous silica, we study the transformation kinetics from monometallic Pt to intermetallic PtSn at different temperatures by a series of time-evolution X-ray diffraction studies. Observations indicate an initial transformation stage mediated by Pt surface-controlled intermixing kinetics, followed by a second stage with distinct transformation kinetics corresponding to a Ginstling–Brounstein (G–B) type bulk diffusion mode. Moreover, the activation barrier for both surface intermixing and diffusion stages is obtained through the development of appropriate kinetic models for the analysis of experimental data. Our density-functional-theory (DFT) calculations provide further insights into the atomistic-level processes and associated energetics underlying surface-controlled intermixing.
DOE Contract Number(s)
DNI-55170; 1507223; AC02-05CH11231; AC02-07CH11358; ACI-1548562
Language
en
Department of Energy Subject Categories
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Publisher
Iowa State University Digital Repository, Ames IA (United States)
Supplementary Information
