A catalyst active to carbon monoxide (CO) oxidation at low temperature is essential for environmental conservation, saving fuel and improvement of the quality of human life. Rational design of CO oxidation catalyst on the basis of comprehensive understanding of physicochemical properties of catalytic materials, rather than simply searching for the catalyst based on trial‐and‐error, is a promising approach to meet the increasingly stringent regulations. This review covers metal‐doped and ‐loaded system based on CeO2 catalysts as strategies to significantly improve CO oxidation activity at low temperature. When incorporated into CeO2 lattice, active metals significantly lower the oxygen vacancy formation energy (Evf) of the catalyst surface, resulting in high catalytic activities at low temperature. When the active metals are loaded on the CeO2 surface, many active sites could be acquired by increasing the dispersion, and the catalytic activity can be dramatically improved by newly introducing the interfacial sites between the metals and the CeO2 support. Doping the support could further improve this loaded system in terms of specific surface area, oxygen vacancy formation, and spillover effects. In this review, based on this knowledge, we propose a rational design approach to a robust low‐temperature CO oxidation catalysts. The desirable CO oxidation catalysts identified from the interplay between theoretical and experimental approaches would ultimately improve the quality of human life, and create potential economic benefits by alleviating air pollution.

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.

Catalyst design with good stability beyond simply having high activity is crucial for a variety of reactions. Here, we evaluate the ceria catalyst for CO oxidation as a model reaction to rationally design an ultrastable catalyst with high activity. The goal was achieved by co-doping with rare-earth (RE) and transition metals (TM) simultaneously. The RE dopant stabilized the catalyst by inhibiting sintering that could lead to catalyst deactivation. The TM dopant increased the activity by facilitating formation of surface defects. Consequently, ceria co-doped with RE (=La, Sm) and TM (=Cu) had increased catalytic activity as well as superior resistance to deactivation during 10 cycle measurement (1 cycle: 900 °C, 24 h → cooling at room temperature → target °C, 24 h) of ∼700 h, which is harsher than any other reported conditions. This approach will shed light on the design of ultrastable oxide materials for a wide range of catalytic reactions.

For oxide-supported metal catalysts, support reducibility and metal dispersion are the key factors to determine the activity and selectivity in many essential reactions involving redox process. Herein, we tuned the exposed surface atoms of the catalyst by facet control and doping methods, which were simultaneously applied to boost the reducibility and metal dispersion of an oxide support. Pd supported on Cu-doped CeO2 (Pd/CDC) for water–gas shift reaction (WGSR) was considered a model system; Cu was doped into the cubic and octahedral CeO2 enclosed with (100) and (111) facets, respectively. By a systematic combination of density functional theory calculations and experimental analyses, the WGSR activity of the Pd/CDC cube was verified to synergistically increase by more than just the sum of the morphology and Cu doping effects. The effect of each tuning method on the activity was further investigated from a mechanistic perspective. This work presents a rational design knowledge to enhance the catalytic activity that can be extended to a wide range of supported metal systems.

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