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Structure Sensitivity of CO Oxidation on Co3O4: A DFT Study

Authors

  • Prof. Dr. Xian-Yong Pang,

    1. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024 (P. R. China)
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  • Chang Liu,

    1. Department of Chemistry and the Tianjin Key Lab of Metal and Molecule-Based Material Chemistry, Nankai University, Tianjin, 300071 (P. R. China)
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  • Dui-Chun Li,

    1. College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024 (P. R. China)
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  • Prof. Cun-Qin Lv,

    1. College of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, Shanxi Province (P. R. China), Fax: (+86) 22-23502458
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  • Prof. Dr. Gui-Chang Wang 

    Corresponding author
    1. College of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, Shanxi Province (P. R. China), Fax: (+86) 22-23502458
    2. Department of Chemistry and the Tianjin Key Lab of Metal and Molecule-Based Material Chemistry, Nankai University, Tianjin, 300071 (P. R. China)
    • College of Chemistry and Chemical Engineering, Shanxi Datong University, Datong 037009, Shanxi Province (P. R. China), Fax: (+86) 22-23502458
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Abstract

The reaction mechanism of CO oxidation on the Co3O4 (110) and Co3O4 (111) surfaces is investigated by means of spin-polarized density functional theory (DFT) within the GGA+U framework. Adsorption situation and complete reaction cycles for CO oxidation are clarified. The results indicate that 1) the U value can affect the calculated energetic result significantly, not only the absolute adsorption energy but also the trend in adsorption energy; 2) CO can directly react with surface lattice oxygen atoms (O2f/O3f) to form CO2 via the Mars–van Krevelen reaction mechanism on both (110)-B and (111)-B; 3) pre-adsorbed molecular O2 can enhance CO oxidation through the channel in which it directly reacts with molecular CO to form CO2 [O2(a)+CO(g)→CO2(g)+O(a)] on (110)-A/(111)-A; 4) CO oxidation is a structure-sensitive reaction, and the activation energy of CO oxidation follows the order of Co3O4 (111)-A(0.78 eV)>Co3O4 (111)-B (0.68 eV)>Co3O4 (110)-A (0.51 eV)>Co3O4 (110)-B (0.41 eV), that is, the (110) surface shows higher reactivity for CO oxidation than the (111) surface; 5) in addition to the O2f, it was also found that Co3+ is more active than Co2+, so both O2f and Co3+ control the catalytic activity of CO oxidation on Co3O4, as opposed to a previous DFT study which concluded that either Co3+ or O2f is the active site.

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