Unraveling\nSerial Degradation Pathways of Supported\nCatalysts through Reliable Electrochemical Liquid-Cell TEM Analysis

Electrochemical\nliquid-cell transmission electron microscopy (e-LCTEM)\noffers great potential for investigating the structural dynamics of\nnanomaterials during electrochemical reactions. However, challenges\narise from the difficulty in achieving the optimal electrolyte thickness,\nleading to inconsistent electrochemical responses and limited spatial\nresolution. In this study, we present advanced e-LCTEM techniques\ntailored for tracking Pt/C degradation under electrochemical polarization\nat short intervals with high spatial resolution. Our innovative approach\ncombines microfabrication-based sample preparation with <i>in\nsitu</i> control of electrolyte thickness, ensuring reliable\nelectrochemical signal acquisition and direct observation of sequential\ncatalyst degradation. Quantitative imaging analyses conducted at both\nglobal areas and single-particle levels unveil a distinctive degradation\nmechanism primarily driven by nanoparticle migrations. Smaller nanoparticles\nexhibit a higher susceptibility to migration, leading to coalescence\nand final detachment in series. This migration-gated degradation mechanism\nprovides a new perspective on the size-dependent durability of supported\nnanoparticles, complementing the prevailing explanation centered on\nthe size-dependent dissolution kinetics of nanoparticles.