Observation of Pt-{100}-p(2×2)-O reconstruction by an environmental TEM

The surface structure of noble metal nanoparticles usually plays a crucial role during the catalytic process in the fields of energy and environment. It has been studied extensively by surface analytic methods, such as scanning tunneling microscopy. However, it is still challenging to secure a direct observation of the structural evolution of surfaces of nanocatalysts in reaction (gas and heating) conditions at the atomic scale. Here we report an in-situ observation of atomic reconstruction on Pt {100} surfaces exposed to oxygen in an environmental transmission electron microscope (TEM). Our high-resolution TEM images revealed that Pt-{100}-p(2×2)-O reconstruction occurs during the reaction between oxygen atoms and {100} facets. A reconstruction model was proposed, and TEM images simulated according to this model with different defocus values match the experimental results well.