Recently, cooperated with Prof. Ya-Wen Zhang’s and Prof. Hai-Chao Liu’s groups, Dr. Rui Si at SINAP (Department of Materials and Energy) has combined the investigation on “structure-activity” relationship in catalysis with the operando X-ray techniques, and made significant progress on the CO oxidation reaction. They have also forwarded an effective approach towards the determination of active site for Pt/CeO₂ catalyst. These results have been published on ACS Catalysis (2015, 5, 5164-5173) as a full article.

CO oxidation (CO+O2→CO₂) is an ideal model reaction in catalysis, and has been widely applied to study the active site of oxide-supported metal catalyst. Previous reports showed that Pt/CeO₂ has high reactivity for the CO oxidation reaction, but the corresponding reaction mechanisms are still in arguments. Prof. Zhang’s group controllably prepared multiple platinum species of single atoms, clusters and nanoparticles on the ceria nanorods by the aids of solution-based chemical synthesis, and found the obviously different catalytic performance of these nanocatalysts on the CO oxidation reaction. Dr. Si used the operando X-ray absorption fine structure (XAFS) measurements, including the linear combination fits on the X-ray absorption near edge spectroscopy (XANES) profiles and the structural fittings on the extended X-ray absorption fine structure (EXAFS) data, to obtain the direct experimental evidences on the active platinum species supported by ceria nanorods. The turnover frequency of Pt/CeO₂ catalyst is inverse proportional to the coordination number of Pt-O shell at the interfaces between platinum and ceria, i. e. strong interaction of Pt-O-Ce is not benefit to the reactivity of CO oxidation. These results will play crucial roles on the development on both design of new Pt/CeO2 catalyst and operando structural characterization.

The related XAFS experiments were carried out at beamlines BL14W1 of SSRF and X18B of NSLS (U.S.). This work was supported by the National Science Foundation of China (NSFC) (grant no. 21373259), the Hundred Talents project of the Chinese Academy of Sciences and the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA09030102).

Structural evolution on platinum-ceria catalyst for CO oxidation reaction detected by operando XAFS