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J Am Chem Soc. 2019 Apr 24;141(16):6690-6697. doi: 10.1021/jacs.9b01882. Epub 2019 Apr 15.

Growth Kinetics of Individual Co Particles Ex-solved on SrTi0.75Co0.25O3-δ Polycrystalline Perovskite Thin Films.

Author information

1
School of Materials Science and Engineering , Gwangju Institute of Science and Technology (GIST) , 123 Cheomdangwagi-ro , Buk-gu, Gwangju , Korea.
2
Department of Materials Science and Engineering , Korea Advanced Institute of Science and Technology (KAIST) , 291 Daehak-ro , Yuseong-gu, Daejeon , Korea.
3
Department of Chemical Engineering , Pohang University of Science and Technology (POSTECH) , 77 Cheongam-ro , Nam-gu, Pohang , Korea.

Abstract

A precise control of the size, density, and distribution of metal nanoparticles dispersed on functional oxide supports is critical for promoting catalytic activity and stability in renewable energy and catalysis devices. Here, we measure the growth kinetics of individual Co particles ex-solved on SrTi0.75Co0.25O3-δ polycrystalline thin films under a high vacuum, and at various temperatures and grain sizes using in situ transmission electron microscopy. The ex-solution preferentially occurs at grain boundaries and corners which appear essential for controlling particle density and distribution, and enabling low temperature ex-solution. The particle reaches a saturated size after a few minutes, and the size depends on temperature. Quantitative measurements with a kinetic model determine the rate limiting step, vacancy formation enthalpy, ex-solution enthalpy, and activation energy for particle growth. The ex-solved particles are tightly socketed, preventing interactions among them over 800 °C. Furthermore, we obtain the first direct clarification of the active reaction site for CO oxidation-the Co-oxide interface, agreeing well with density functional theory calculations.

PMID:
30938992
DOI:
10.1021/jacs.9b01882

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