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Science Advances  25 Jan 2019: Vol. 5, no. 1, eaau9590

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

Wenpei Gao1, Peter Tieu2, Christopher Addiego3, Yanling Ma4, Jianbo Wu4,5,6,* and Xiaoqing Pan1,3,*

1Department of Materials Science and Engineering, University of California, Irvine, CA 92697, USA.
2Department of Chemistry, University of California, Irvine, CA 92697, USA.
3Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA.
4State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
5Center of Hydrogen Science, Shanghai Jiao Tong University, Shanghai 200240, China.
6Materials Genome Initiative Center, Shanghai Jiao Tong University, Shanghai 200240, China.
*Corresponding author. Email: xiaoqing.pan@uci.edu (X.P.); jianbowu@sjtu.edu.cn (J.W.)

Science Advances  25 Jan 2019: Vol. 5, no. 1, eaau9590, DOI: 10.1126/sciadv.aau9590

Control of reduction kinetics and nucleation processes is key in materials synthesis. However, understanding of the reduction dynamics in the initial stages is limited by the difficulty of imaging chemical reactions at the atomic scale; the chemical precursors are prone to reduction by the electron beams needed to achieve atomic resolution. Here, we study the reduction of a solid-state Pt precursor compound in an aberration-corrected transmission electron microscope by combining low-dose and in situ imaging. The beam-sensitive Pt precursor, K2PtCl4, is imaged at atomic resolution, enabling determination of individual (K, Pt, Cl) atoms. The transformation to Pt nanoclusters is captured in real time, showing a three-stage reaction including the breaking of the ionic bond, formation of PtCl2, and the reduction of the dual-valent Pt to Pt metal. Deciphering the atomic-scale transformation of chemicals in real time using combined low-dose and in situ imaging brings new possibility to study reaction kinetics in general.

 

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