Gao Wenpei, Tieu Peter, Addiego Christopher, Ma Yanling, Wu Jianbo, Pan Xiaoqing
Department of Materials Science and Engineering, University of California, Irvine, CA 92697, USA.
Department of Chemistry, University of California, Irvine, CA 92697, USA.
Sci Adv. 2019 Jan 25;5(1):eaau9590. doi: 10.1126/sciadv.aau9590. eCollection 2019 Jan.
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, KPtCl, 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 PtCl, 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.
控制还原动力学和成核过程是材料合成的关键。然而，由于在原子尺度上对化学反应进行成像存在困难，对初始阶段还原动力学的理解受到限制；化学前驱体容易被实现原子分辨率所需的电子束还原。在这里，我们通过结合低剂量和原位成像，在像差校正透射电子显微镜中研究固态铂前驱体化合物的还原过程。对光束敏感的铂前驱体KPtCl进行原子分辨率成像，能够确定单个（K、Pt、Cl）原子。实时捕捉到向铂纳米团簇的转变，显示出一个三阶段反应，包括离子键的断裂、PtCl的形成以及二价铂还原为铂金属。使用低剂量和原位成像相结合的方法实时解析化学物质的原子尺度转变，总体上为研究反应动力学带来了新的可能性。
