▎ 摘　　要

The real-time investigations of coarsening process and microstructural transformation are instrumental in elucidating the thermal stability, ripening dynamics and coalescing microstructures of metal nanocatalysts in thermocatalytic reactions. Herein, we conducted an in-situ transmission electron microscopy (TEM) study on reduced graphene oxide-based platinum nanocatalysts (Pt/rGO). The platinum nanoparticles (PtNPs) exhibited superior thermal stability on the rGO flat surface than on the wrinkle one, indicating that improving the surface flatness of graphene-based supports can increase the thermal stability of deposited metal nanocatalysts. The timeresolved analysis demonstrated that the thermal-induced microstructural transformation (graphitization) of the rGO support caused the discrepancy of PtNPs coarsening from the Ostwald ripening model. The in-situ highresolution images further revealed the coalescing microstructures of PtNPs on the graphitized rGO, which validated the previous simulation research by real-time experimental observations.