Stepwise displacement of catalytically active gold nanoparticles on cerium oxide.

Aberration-corrected environmental transmission electron microscopy (ETEM) proved that catalytically active gold nanoparticles (AuNPs) move reversibly and stepwise by approximately 0.09 nm on a cerium oxide (CeO2) support surface at room temperature and in a reaction environment. The lateral displacements and rotations occur back and forth between equivalent sites, indicating that AuNPs are loosely bound to oxygen-terminated CeO2 and may migrate on the surface with low activation energy. The AuNPs are likely anchored to oxygen-deficient sites. Observations indicate that the most probable activation sites in gold nanoparticulate catalysts, which are the perimeter interfaces between an AuNP and a support, are not structurally rigid.