In Situ Microscopy and Spectroscopy Study on Dynamics of Nanostructure in Catalysis for Sustainable Energy

Understanding the atomistic structure of the active site during catalytic reactions is of paramount importance in both fundamental studies and practical applications, but such studies are challenging due to the complexity of heterogeneous systems. Using Pt/CeO₂ as an example, we reveal the dynamic nature of active sites during the water-gas-shift reaction (WGSR) by combining multiple in situ characterization tools to study well-defined CeO₂ nanoshapes with different exposed facets. In situ near-ambient pressure X-ray photoelectron spectroscopy shows that metallic Pt is present on the CeO₂(111) surfaces, while oxidized Pt species are dominant on CeO₂(110) and (100) surfaces after O₂–H₂ pretreatment. The different concentrations of interfacial Pt^δ+ – O – Ce⁴⁺ moieties at Pt/CeO₂ interfaces are responsible for the rank of catalytic performance of Pt/CeO₂ catalysts: Pt/CeO₂-rod > Pt/CeO₂-cube > Pt/CeO₂-oct. For all the catalysts, metallic Pt is formed during the WGSR, leading to the transformation of the active sites to Pt⁰ – O_v – Ce³⁺ and interface reconstruction, which is demonstrated by the in situ environmental transmission electron microscopy. These findings shed light on the dynamics nature of nanostructures under operating conditions and highlight the importance of combining complementary in situ techniques for establishing structure-performance relationships.