Fabrication of Ag-CeO2 core-shell nanospheres with enhanced catalytic performance due to strengthening of the interfacial interactions

摘要

Interfacial interactions are often found in human medical devices, hybrid solar cells, and catalysis. However, there is a lack of control of these interactions when tailoring the materials properties for many technological applications. As a case study, we reported on the synthesis of Ag-CeO2 core-shell nanospheres with the aim of strengthening the interfacial interactions to give enhanced catalytic performance. All core-shell nanospheres were synthesized by a surfactant-free method with a subsequent annealing redox reaction. Systematic sample characterizations indicate that metallic Ag cores with a diameter of 50-100 nm were wrapped by assembled nanoparticles of CeO2 with a shell thickness of 30-50 nm to form a nano-scale core-shell structure. The interfacial interactions between the Ag core and CeO2 shell were strengthened by annealing, surprisingly, as followed by generation of oxygen vacancies to provide abundant of absorption sites for oxygen species. As a consequence, the temperature for oxygen spilling was lowered to 79 °C, and the catalytic performance was abnormally enhanced, as indicated by complete CO oxidation at 120 °C with no sign of deactivation, even when the reaction time is beyond 100 h. The reaction products were desorbed quickly from the surfaces of the core-shell nanospheres, which accounts for their superior stability during catalytic reactions.