Metal-support interactions are believed to significantly affect the reactivity, selectivity, and stability of oxide-supported metal nanocatalysts and represent an effective tuning factor to achieve optimized catalyst performance. Reported mechanisms for the effects of the support on catalytic performance mainly include small-cluster stabilization, support participation in catalysis, oxide encapsulation of metal nanoparticles, and charge transfer processes. These mechanisms are typically associated with the structure and chemistry of the materials, which can now be routinely accessed by various high-resolution microscopy techniques. Our understanding of charge transfer in heterogenous catalysis, however, is limited by a lack of reliable and accessible techniques capable of directly studying this phenomenon at its inherent nanometer length scale and learning its correlations with interfacial atomic configurations. In this presentation, I will report our recent advancements of four-dimensional scanning transmission electron microscopy (4D-STEM) techniques to map nanometer-scale charge redistribution simultaneously with atomic structures around individual nanoparticles. I will further demonstrate that the direction of charge transfer can be inverted using surface treatments of support, which has thus far primarily been predicted theoretically. By pairing the 4D-STEM results with density functional theory (DFT) calculations, atomic-scale mechanisms responsible for the highly active perimeter sites of metal/oxide catalysts are also revealed.

Probe charge transfer on the sub-nm scale in heterogenous catalysts <i>via</i> 4D-STEM

ACS Spring 2022

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

Probe charge transfer on the sub-nm scale in heterogenous catalysts via 4D-STEM