Detail:
Abstract: Synthesizing nanocrystals with precisely controlled size, shape, and structure is of great importance for understanding their properties, especially catalysis. Although significant developments have been achieved in colloidal synthesis in the past two decades, it remains challenging to synthesize nanocrystal catalysts in a predictive way due to a lack of mechanistic understanding of the synthesis. In this seminar, I will discuss my recent research efforts on using synchrotron-based X-ray scattering to investigate the formation mechanisms of nanocrystals in real time under typical colloidal synthetic conditions. The first part of this talk describes using in situ small angle X-ray scattering (SAXS) to elucidate the formation kinetics of monometallic Pd nanocrystals in the presence of different ligands. The quantitative understanding provides the basis for precisely synthesizing a broad library of monodisperse Pd nanocrystals with 1 nm size control. In the second part, I will discuss an unprecedented rapid crystallization of nanocrystals into three-dimensional superlattices at high temperatures and their continuous growth within the superlattice structures observed using in situ SAXS, which provides new insights on interparticle interactions during colloidal synthesis. Finally, by coupling the SAXS with the wide angle X-ray scattering (WAXS), I will demonstrate that the in situ X-ray scattering allows us to study the formation of bimetallic PtSn nanocrystals at the atomic scale. This type of in situ characterization can be readily extended to other multimetallic systems to advance their synthetic design.
