Fast Prediction of CO Oxidation Activity on Rare-Earth Metal Doped CeO2

Fast Prediction of CO Oxidation Activity on Rare-Earth Metal Doped CeO₂

 

Kyeounghak Kim¹, JeongDo Yoo², Siwon Lee², WooChul Jung², and Jeong Woo Han^1,*

¹Department of Chemical Engineering, University of Seoul, Seoul 130-743, Republic of Korea

²Department of Materials Science and Engineering, Korea Advanced Institute of Technology, Daejeon 305-701, Republic of Korea

*E-mail: jwhan@uos.ac.kr

Owing to high oxygen storage capacity and high stability over the wide range of temperatures, CeO₂ has been widely applied to support materials for the electrode of solid oxide fuel cells or diverse oxidation catalysts. While there have been several studies for understanding the catalytic activity according to the rare-earth (RE) metal dopants on CeO₂ nanoparticles, it is hard to find the detailed reaction mechanism and a simple descriptor which enables to rapidly estimate the activity. In this study, our combinatorial study of experiments and theories shows the catalytic activities of CO oxidation are in order of CeO₂ > Ce_0.8Pr_0.2O₂ (PDC) > Ce_0.8Nd_0.2O₂ (NDC) > Ce_0.8Sm_0.2O₂ (SDC). Our density functional theory calculations demonstrated that CO oxidation reaction on RE-doped CeO₂(111) is well described via the Mars-Van Krevelen (MvK) mechanism (Fig. 1). We found that the ionic radius of dopants can be used as a simple descriptor to predict the whole reaction activity (Fig. 2). Based on our results, we suggest that La might be a promising dopant to enhance the catalytic activity of CO oxidation. Our results will provide useful insight to unravel and predict the CO oxidation activity of ceria based catalysts.

Figure 1 Relative energy diagram of CO oxidation on RE-doped CeO₂(111).

 

Figure 2 Linear relationship between maximum reaction energy for CO oxidation and ionic radius of dopants on RE-doped CeO₂(111).