Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped T...Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped ThO2 using density functional theory with Hubbard-type on-site Coulomb interaction （DFT ＋ U）. The calculation results show that the Au-doped THO2（111） catalyst exhibits remarkable catalytic activity for CO oxidation via the Eley-Rideal mechanism in three steps, where the rate-determining step is decomposition of the OCOO＋ intermediate with an energy barrier of 0.58 eV. Moreover, our results also reveal a new mechanism of CO oxidation on a gold adatom supported by THO2（111）, where O2 is adsorbed only at the Th site on the surface, and the gas-phase CO then reacts directly with the activated O2＋ to form CO2, which is the rate-limiting step, with a barrier of 0.46 eV. It is found that CO oxidation can occur without CO and O2 coadsorption on Au, which was previously considered a key intermediate. Therefore, these results provide new insights into CO oxidation on isolated gold atoms supported by the 5f-element compound THO2（111）. This mechanism can help clarify the catalytic cycle of CO oxidation, support the design of high- performance low-cost catalysts, and elucidate the redox properties of actinide oxides.展开更多
基金The calculations were supported by the National Basic Research Program of China （No. 2013CB834603） and National Natural Science Foundation of China （Nos. 91426302, 21590792, and 21433005） and were performed using supercomputers at Tsinghua National Laboratory for Information Science and Technology and the Supercomputing Center, Computer Network Infor- mation Center of the Chinese Academy of Sciences.
文摘Single-atom catalysts are of great interest and importance for designing new high-performance low-cost catalysts. We investigated CO oxidation catalyzed by single gold atoms supported on thoria （Au/ThO2） and doped ThO2 using density functional theory with Hubbard-type on-site Coulomb interaction （DFT ＋ U）. The calculation results show that the Au-doped THO2（111） catalyst exhibits remarkable catalytic activity for CO oxidation via the Eley-Rideal mechanism in three steps, where the rate-determining step is decomposition of the OCOO＋ intermediate with an energy barrier of 0.58 eV. Moreover, our results also reveal a new mechanism of CO oxidation on a gold adatom supported by THO2（111）, where O2 is adsorbed only at the Th site on the surface, and the gas-phase CO then reacts directly with the activated O2＋ to form CO2, which is the rate-limiting step, with a barrier of 0.46 eV. It is found that CO oxidation can occur without CO and O2 coadsorption on Au, which was previously considered a key intermediate. Therefore, these results provide new insights into CO oxidation on isolated gold atoms supported by the 5f-element compound THO2（111）. This mechanism can help clarify the catalytic cycle of CO oxidation, support the design of high- performance low-cost catalysts, and elucidate the redox properties of actinide oxides.
