Jacob Smith, Wenpei Gao Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA The properties of nanocatalysts are modified by their morphology. Improved understanding of the dynamics that drive the formation of the desired nanostructure is thus critical. For a given manufacturing process, there may be a number of intermediary steps that connect the initial reagents and final products. Visualizing these intermediary steps presents an opportunity to better control the reaction kinetics. Today, it is possible to use atomic resolution transmission electron microscopy (TEM) to observe these intermediary steps as they occur and obtain a more complete knowledge of a manufacturing process’ dynamics. In this study, the decomposition of a chemical precursor of Pt metal, K2PtCl4, has been monitored in solid state in TEM so that its intermediary steps could be revealed. Crystallites of K2PtCl4, a typical precursor to synthesize Pt nanoparticles, were imaged in an aberration corrected scanning transmission electron microscope (STEM) operated at 200 keV, using both high angle annular dark field (HAADF) and differential phase contrast (DPC) detectors. The HAADF and DPC images reveal the position and structures of Pt atoms and light atoms including K and Cl simultaneously. The reaction dynamics were captured on sequential frames so that both the mechanisms and kinetics could be understood. The experimental images were later compared to images simulated using a multislice algorithm to aid in data interpretation. This presentation will describe the dynamics that control the solid-state decomposition of K2PtCl4 into its final products, with the intermediary steps detailed at atomic resolution. These findings demonstrate the potential of TEM in future nanocatalyst research and design by revealing previously unknown mechanisms and interfacial effects that influence the transition of a catalyst precursor.

Atomic resolution electron microscopy of solid-state phase transformations and chemical reduction

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.