In Situ Neutron Scattering Studies on the Oxidation and Reduction of CeO2 and Pt–CeO2 Nanorods

Abstract

The oxygen vacancy structure of ceria plays a key role in its performance as a favored material for catalysis applications. Here, we develop an understanding of the effects of Pt loading on the structural evolution of ceria nanorods under redox gas environments that mimic real automotive catalytic converters. In situ neutron scattering studies under redox flow reveal that both CeO2 and Pt–CeO2 nanorods share a bulk fluorite structure with the presence of surface Frenkel-type oxygen defects. However, Pt–CeO2 nanorods are more easily reducible than CeO2 rods as evidenced by an increased concentration of Ce3+, determined by NAP-XPS. Importantly, this work finds no evidence of oxygen vacancy ordered surface reconstruction which has been reported in earlier ex situ investigations. Thus, this work highlights the discrepancy between ex situ and in situ structural observations and emphasizes the need for robust in situ investigations of catalysts to develop industrially relevant materials.