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)

IS-J 9927 SI.pdf (2077 kB)
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