Unraveling Serial Degradation Pathways of Supported Catalysts through Reliable Electrochemical Liquid-Cell TEM Analysis

Electrochemical liquid-cell transmission electron microscopy (e-LCTEM) offers great potential for investigating the structural dynamics of nanomaterials during electrochemical reactions. However, challenges arise from the difficulty in achieving the optimal electrolyte thickness, leading to inconsistent electrochemical responses and limited spatial resolution. In this study, we present advanced e-LCTEM techniques tailored for tracking Pt/C degradation under electrochemical polarization at short intervals with high spatial resolution. Our innovative approach combines microfabrication-based sample preparation with control of electrolyte thickness, ensuring reliable electrochemical signal acquisition and direct observation of sequential catalyst degradation. Quantitative imaging analyses conducted at both global areas and single-particle levels unveil a distinctive degradation mechanism primarily driven by nanoparticle migrations. Smaller nanoparticles exhibit a higher susceptibility to migration, leading to coalescence and final detachment in series. This migration-gated degradation mechanism provides a new perspective on the size-dependent durability of supported nanoparticles, complementing the prevailing explanation centered on the size-dependent dissolution kinetics of nanoparticles.