Fan Yang, State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, China

Interfacial catalysis over well-defined oxide nanostructures

The catalytic properties of nano-oxides are increasingly recognized and currently explored for a wide range of applications. However, the nature of the active sites of these nano-oxides, as well as their catalytic chemistry, remain poorly understood, because of the difficulties to access these surface/interfacial sites at the atomic level. Using molecular beam epitaxy, we construct well-defined oxide nanostructures (NSs) on planar metal or oxide surfaces, which serve as the model systems for understanding the catalytic chemistry of the metal-oxide interface and nano-oxides. In this talk, we report our recent progress in the studies of low temperature CO oxidation and CO disproportionation reaction, using supported FeO and CeO_x NSs as the model catalysts. The FeO-Pt interface has been suggested to exhibit remarkable activity in the preferential oxidation of CO (PROX) in excess H₂.^1-2 Combining microscopic and spectroscopic methods, CO oxidation was investigated at the FeO-Pt interface, to understand the mechanism of low temperature CO oxidation and the catalytic properties of the metal-oxide interface. Size effect was further investigated using different-sized FeO NSs as the model system³ and a dynamic size effect was demonstrated that could govern the chemical properties of NSs⁴ and the catalytic process. In addition, we report our recent study on the CO disproportionation reaction. Owing to the weak interaction between CO and oxide surfaces, CO disproportionation has been considered impossible on planar ceria surfaces. In contrast, we show by controlling the size and coordination number of ceria NSs, such reaction could be observed on nanostructured ceria surfaces. Overall, we wish to demonstrate that the control over supported oxide NSs could enable a wide range of catalytic properties for the rational design of highly efficient catalysts.

References

1. Fu, Q.; Li, W.-X.; Yao, Y.; Liu, H.; Su, H.-Y.; Ma, D.; Gu, X.-K.; Chen, L.; Wang, Z.; Zhang, H.; Wang, B.; Bao, X., Interface-Confined Ferrous Centers for Catalytic Oxidation. Science 2010, 328 (5982), 1141-1144.
2. Fu, Q.; Yang, F.; Bao, X., Interface-Confined Oxide Nanostructures for Catalytic Oxidation Reactions. Acc. Chem. Res. 2013, 46 (8), 1692-1701.
3. Liu, Y.; Ning, Y.; Yu, L.; Zhou, Z.; Liu, Q.; Zhang, Y.; Chen, H.; Xiao, J.; Liu, P.; Yang, F.; Bao, X., Structure and Electronic Properties of Interface-Confined Oxide Nanostructures. ACS Nano 2017, 11 (11), 11449-11458.
4. Liu, Y.; Yang, F.; Zhang, Y.; Xiao, J.; Yu, L.; Liu, Q.; Ning, Y.; Zhou, Z.; Chen, H.; Huang, W.; Liu, P.; Bao, X., Enhanced Oxidation Resistance of Active Nanostructures via Dynamic Size Effect. Nat. Commun. 2017, 8, 14459.

Host: Associate professor Jeppe Vang Lauritsen, iNANO & Dept. of Physics and Astronomy, AU