Rational Design of Transition Metal Co‐Doped Ceria Catalysts for Low‐Temperature CO Oxidation

Abstract

We present a highly active CeO 2 -based catalyst for oxidizing CO in automobile exhaust. This catalyst was systemically designed by co-doping with transition metals (TMs). First, we used density functional theory (DFT) calculations to screen Mn and 13 dopant TMs (periods 4~6 in groups VIII~XI) and their 91 binary combinations for co-doping. As a result, Cu and (Cu, Ag) were found to be the best candidates among the single and binary dopants, respectively. Next, we synthesized CeO 2 nano-particles doped with Cu or (Cu, Ag), then experimentally confirmed that the predicted (Cu, Ag) co-doped CeO 2 showed higher activity than pure CeO 2 and other TM-doped CeO 2 . This was attributed to the easy formation of oxygen vacancies in the lattice of CeO 2 . Our study demonstrates that the use of a rational design of CeO 2 -based catalyst through theoretical calculations and experimental validation can effectively improve the low-temperature catalytic activity of CO oxidation.

Design of Ceria Catalysts for Low‐Temperature CO Oxidation

“…reported that TM‐co‐doped CeO 2 catalyst had a critical effect on catalytic activity . Our group performed theoretical analysis of these results and reported a linear correlation between E vf and catalytic activity in co‐doping as well as in single‐metal doping . In addition, it is very important to select co‐doping combination candidates because the catalytic activity differs depending on the co‐dopant, as confirmed by Park et al…”

“…In this sense, the energy required to detach a lattice oxygen atom from the surface, that is oxygen vacancy formation energy ( E vf ), can be considered as a feasible descriptor to describe the activity of CO oxidation. In many previous studies, the E vf showed inverse correlation with the measured catalytic activity of CO oxidation on doped or undoped CeO 2 (111), suggesting that lower E vf of a CeO 2 ‐based catalyst enhanced its activity . Therefore, E vf can be used to effectively predict the activity of CeO 2 ‐based catalysts in CO oxidation.…”

“…[83] Our group performed theoretical analysis of these results and reported a linear correlation between E vf and catalytic activity in co-doping as well as in single-metal doping. [33,54] In addition, it is very important to select co-doping combination candidates because the catalytic activity differs depending on the co-dopant, as confirmed by Park et al [83] Our previous study developed an excellent co-doping catalyst using E vf obtained via DFT calculations. Using Mn and 13 TMs (periods 4~6 in groups 8~11), E vf for 91 binary combinations and single dopants were screened (Figure 5b).…”

“…In many previous studies, the E vf showed inverse correlation with the measured catalytic activity of CO oxidation on doped or undoped CeO 2 (111), suggesting that lower E vf of a CeO 2 -based catalyst enhanced its activity. [32,[51][52][53][54] Therefore, E vf can be used to effectively predict the activity of CeO 2 -based catalysts in CO oxidation. Therefore, facilitating the formation of oxygen vacancy on the catalyst surface by doping aliovalent metals is a highly promising strategy to improve low-temperature CO oxidation.…”

“…Here, we review the papers that introduce TM co-doped CeO 2 systems to exhibit the catalytic activity at lower temperature than single-doped CeO 2 catalysts. [33,54,[83][84][85] It is possible to develop materials with high catalytic activity at low temperature by clearly identifying the descriptors that increase the catalytic activity depending on the dopant metal (Figure 5a). Park et al reported that TM-co-doped CeO 2 catalyst had a critical effect on catalytic activity.…”