Smith Jacob G, Sawant Kaustubh J, Zeng Zhenhua, Eldred Tim B, Wu Jianbo, Greeley Jeffrey P, Gao Wenpei
Future Material Innovation Center, Zhangjiang Institute for Advanced Study, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA.
Sci Adv. 2024 Feb 9;10(6):eadi0175. doi: 10.1126/sciadv.adi0175.
The direct observation of a solid-state chemical reaction can reveal otherwise hidden mechanisms that control the reaction kinetics. However, probing the chemical bond breaking and formation at the molecular level remains challenging because of the insufficient spatial-temporal resolution and composition analysis of available characterization methods. Using atomic-resolution differential phase-contrast imaging in scanning transmission electron microscopy, we have visualized the decomposition chemistry of KPtCl to identify its transient intermediate phases and their interfaces that characterize the chemical reduction process. The crystalline structure of KPtCl is found to undergo a disproportionation reaction to form KPtCl, followed by gradual reduction to crystalline Pt metal and KCl. By directly imaging different Pt─Cl bond configurations and comparing them to models predicted via density functional theory calculations, a causal connection between the initial and final states of a chemical reaction is established, showcasing new opportunities to resolve reaction pathways through atomistic experimental visualization.
对固态化学反应的直接观察可以揭示控制反应动力学的其他隐藏机制。然而，由于现有表征方法的时空分辨率和成分分析不足，在分子水平上探测化学键的断裂和形成仍然具有挑战性。利用扫描透射电子显微镜中的原子分辨率差分相衬成像，我们可视化了KPtCl的分解化学过程，以识别其瞬态中间相及其表征化学还原过程的界面。发现KPtCl的晶体结构发生歧化反应形成KPtCl，随后逐渐还原为晶体铂金属和KCl。通过直接成像不同的Pt-Cl键构型并将它们与通过密度泛函理论计算预测的模型进行比较，建立了化学反应初始状态和最终状态之间的因果联系，展示了通过原子实验可视化解析反应途径的新机会。
