Research ArticleMATERIALS SCIENCE

Probing the dynamics of nanoparticle formation from a precursor at atomic resolution

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Science Advances  25 Jan 2019:
Vol. 5, no. 1, eaau9590
DOI: 10.1126/sciadv.aau9590
  • Fig. 1 Low-dose atomic resolution imaging of K2PtCl4.

    (A) The atomic model of the K2PtCl4 unit cell, with K in cyan, Pt in purple, and Cl in pink. (B) Bright-field TEM image of a large K2PtCl4 crystallite. (C) Diffraction pattern of the K2PtCl4 crystallite in (B) after it is tilted along the (001) zone axis. (D) Atomic resolution low-dose TEM image of K2PtCl4. Dose fractionation was done using an electron dose of 1 e/Å2·s, with 0.1 s for each image. Sixty-four images were acquired, aligned, and averaged. The electron dose then becomes 6.4 e/Å2. The atomic model is overlaid in the inset. (E) Simulated HREM image of K2PtCl4 with a thickness of 12.3 nm. (F) A zoomed-in image of K2PtCl4 from a sub-area in (D), and the intensity line profile in arbitrary units (a.u.) from the red box, is shown in (G), where the intensity from Pt atoms is located between two Cl atoms.

  • Fig. 2 Evolution of K2PtCl4 into Pt nanoparticles.

    (A) Sequential TEM images show the evolution of K2PtCl4 into Pt nanoparticles. A Pt nanoparticle nucleation process is shown in the zoomed-in images in (B), from the marked sub-area within the white dashed boxes in (A). The red contour lines indicate the edge of the newly formed Pt clusters. The region in yellow highlights the void area without lattice after the formation of a Pt cluster.

  • Fig. 3 Sequential RDF during the transformation.

    (A) Time series diffractogram using FFT from sequential low-dose images. (B) RDF derived from the sequential diffractogram.

  • Fig. 4 Composition analysis of the ending product.

    (A to D) HAADF image and EDS maps of the ending product of the in situ experiment and (E) EELS of the ending product of the in situ experiment showing the existence of Cl and K.

  • Fig. 5 A schematic showing the evolution of K2PtCl4 into Pt nanoparticles.

    (A) K2PtCl4, (B) dissociation of K+ and [PtCl4]2−, (C) further dissociation into PtCl2 and KCl, and (D) nucleation of Pt nanoparticles.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/1/eaau9590/DC1

    Fig. S1. Low-dose TEM image of K2PtCl4.

    Fig. S2. Atomic resolution low-dose TEM image of K2PtCl4.

    Fig. S3. Zoomed-in image and atomic model of K2PtCl4.

    Fig. S4. Low-dose TEM image and diffraction pattern of K2PtCl4.

    Fig. S5. HREM simulation of K2PtCl4.

    Fig. S6. Small Pt clusters grown on the matrix of K2PtCl4.

    Fig. S7. Sequential low-dose TEM images of K2PtCl4.

    Fig. S8. Sequential FFT and RDF.

    Fig. S9. Analysis of the time-evolving RDF.

    Movie S1. Low-dose HREM of the K2PtCl4 crystal using K2 dose fractionation.

    Movie S2. In situ imaging of the reduction dynamics and the formation of Pt clusters.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Low-dose TEM image of K2PtCl4.
    • Fig. S2. Atomic resolution low-dose TEM image of K2PtCl4.
    • Fig. S3. Zoomed-in image and atomic model of K2PtCl4.
    • Fig. S4. Low-dose TEM image and diffraction pattern of K2PtCl4.
    • Fig. S5. HREM simulation of K2PtCl4.
    • Fig. S6. Small Pt clusters grown on the matrix of K2PtCl4.
    • Fig. S7. Sequential low-dose TEM images of K2PtCl4.
    • Fig. S8. Sequential FFT and RDF.
    • Fig. S9. Analysis of the time-evolving RDF.

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.avi format). Low-dose HREM of the K2PtCl4 crystal using K2 dose fractionation.
    • Movie S2 (.avi format). In situ imaging of the reduction dynamics and the formation of Pt clusters.

    Files in this Data Supplement:

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