Aberration-Corrected Imaging of Active Sites on Industrial Catalyst Nanoparticles

Abstract

The active components of industrial heterogeneous catalysts are often small metallic particles, whose reactivity and selectivity depend on the presence of steps and kinks on their surfaces. Although scanning probe microscopy can be used to identify the roles of active sites on the extended surfaces of model catalysts, little is known about atomic arrangements on the surfaces of commercial catalyst nanoparticles, as highlighted by a recent study of ammonia synthesis in a Ru-catalyzed reaction. High-resolution transmission electron microscopy (HRTEM) has been used extensively to characterize such particles.[2] However, conventional HRTEM images are affected by electron microscope objective lens aberrations, limiting spatial resolution, and complicating interpretation. The visibility of nanoparticles can also be affected by strong phase contrast from their support. Here, we show that spherical-aberration-corrected transmission electron microscopy (TEM) can be used to provide atomic-resolution information about the local topologies of active sites on commercial nanoparticles with greatly improved sensitivity.