Atomically Resolved Anisotropic Electrochemical Shapingof Nano-electrocatalyst

摘要

Catalytic properties of advanced functional materials are determined by their surface and near-surface atomic structure, composition, morphology, defects, compressive and tensile stresses, etc; also known as a structure–activity relationship. The catalysts structural properties are dynamically changing as they perform via complex phenomenon dependent on the reaction conditions. In turn, not just the structural features but even more importantly, catalytic characteristics of nanoparticles get altered. Definitive conclusions about these phenomena are not possible with imaging of random nanoparticles with unknown atomic structure history. Using a contemporary PtCu-alloy electrocatalyst as a model system, a unique approach allowing unprecedented insight into the morphological dynamics on the atomic-scale caused by the process of dealloying is presented. Observing the detailed structure and morphology of the same nanoparticle at different stages of electrochemical treatment reveals new insights into atomic-scale processes such as size, faceting, strain and porosity development. Furthermore, based on precise atomicallyresolved microscopy data, Kinetic Monte Carlo (KMC) simulations providefurther feedback into the physical parameters governing electrochemicallyinduced structural dynamics. This work introduces a unique approachtoward observation and understanding of nanoparticles dynamic changeson the atomic level and paves the way for an understanding of thestructure–stability relationship.