Revealing high temperature stability of platinum nanocatalysts deposited on graphene oxide by in-situ TEM

This study reveals atomic-scale observations of the high temperature stability of platinum nanoparticles deposited on pristine graphene oxide (PtNPs/GO) and platinum nanoparticles deposited on water-etched graphene oxide (PtNPs/GO-H2O) as two representative catalyst systems for dehydrogenation. With the aid of in-situ transmission electron microscopy (TEM), these two kinds of catalysts can be examined at actual working temperatures up to 800 degrees C, and notably, PtNPs/GO-H2O exhibits the higher temperature stability even at 700 degrees C. The statistical data of in-situ time-lapsed TEM images demonstrate the size variations of the sintering Pt nanoparticles which are in accordance with the Ostwald ripening process. We further discover the tendency towards the preferential exposure of high-index Pt nanocrystal facets (higher surface energy sides) for the PtNPs/GO under thermal treatment from 25 degrees C to 400 degrees C, which leads to accelerate the nanoparticle aggregations, providing microscopic evidence of the catalyst instability at high temperatures.