<i>In-situ</i> TEM investigation of the oxidation mechanism in highly efficient AuCu alloy nanoparticles

Bimetallic catalysts are extensively utilized in heterogeneous catalysis due to their superior performance. The catalytic efficiency of these catalysts is influenced by various factors, particularly their structure and active sites, which are often overlooked in terms of mechanism and evolution. Herein, we present AuCuO/Al₂O₃, which feature active CuO island structures on its surface, demonstrating exceptional catalytic oxidative dehydrogenation performance with isopropanol. Compared with untreated AuCu/Al₂O₃, AuCuO/Al₂O₃ shows significantly enhanced activity, with nearly an order of magnitude improvement in catalytic performance at low temperatures. This enhancement is attributed to the element segregation process and the positive effect of Cu structures on catalytic activity. Theoretical simulations reveal that Cu and Au elements migrate in opposite directions, leading to the formation of CuO islands. <i>In-situ</i> transmission electron microscopy (TEM) images under oxidizing and thermal conditions elucidated the evolution of these structures. This work uncovers the evolution mechanism of active structures and interfaces in bimetallic catalysts, offering insights into the construction of interfacial sites and optimization of catalyst structures for high-performance applications.