Tracking the dynamics of catalytic Pt/CeO₂ active sites during water-gas-shift reaction

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. Here, we use Pt/CeO₂ as an example to study the dynamic nature of active sites during the water-gas-shift reaction (WGSR) by combining multiple in situ characterization tools. We show that 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. These findings shed light on the nature of the active site for the WGSR on Pt/CeO₂ and highlight the importance of combining complementary in situ techniques for establishing structure-performance relationships. (Figure presented.)