Relationships Between Structural Inhomogeneities at Atomic-Scale and Functional Properties

Catalytic activity is highly influenced by the bonding of reactants to solid surfaces to modulate the energetic barriers that must be overcome. The strengths of these bonds can be modified by the choice of material composition and control of the atomic arrangements. For example, researchers have found that deformation in the crystal lattice (strain) significantly affects catalytic activity. In turn, the strain distribution can be tailored by defects, grain boundaries, and the interaction of the catalyst with underlying support.<br/>In this work, we employ high-resolution transmission electron microscopy (TEM) to investigate the atomic structures of heterogeneous catalysts (e.g., Pt supported on TiO₂ nanoparticles), focusing on the detailed characterization of their structure, including bonding states, strain distribution, defects, and grain boundaries, especially at the contact areas of nanoparticle assemblies and the interfaces of catalyst with underlying support. In addition, using in-situ TEM, we explore kinetics and dynamics of catalytic reactions upon exposure to various conditions at the surfaces of catalysts and the interfaces of catalyst and support materials by observing the evolution of the surface structures of nanoparticles and the active epitaxial sites at the interfaces. The experimental results based on the structural analysis and catalytic activity tests corroborated with <i>ab initio</i> simulations based on the density functional theory to explore the structure-function relationships and establish factors responsible for the enhanced catalytic activity. This provides an insight that allows utilizing the structural inhomogeneities and designing surface structures and compositions for tailored functionality of catalytic materials.