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Calculations of NO Reduction with CO over a Cu1/PMA Single–Atom Catalyst: A Study of Surface Oxygen Species, Active Sites, and Reaction Mechanism

Abstract

Density functional theory calculations have been employed to probe the reaction mechanism of NO reduction with CO over a Cu1/PMA (PMA is the phosphomolybdate, Cs3PMo12O40) single–atom catalyst (SAC). Several important aspects of the catalytic system were addressed, including the generation of oxygen vacancy (Ov), formation of N2O2 intermediates, scission of N–O bond of N2O2 intermediates to form N2O or N2, and decomposition of N2O to form N2. Unlike most previous theoretical studies, which tends to explore the reaction mechanism of polyoxometalates (POM) system based on the isolated anionic unit, here, we build a model of the catalytic system with neutral species by introducing countering cations to model the solid structure of Cu1/PMA SAC. The major findings of our present study are: (1) CO adsorption on Cu site leads to the formation of cationic Cu carbonyl species; (2) the Oc atom at the surface of the PMA support can easily react with the adsorbed CO to generate the Cu–Ov pair; (3) the Cu–Ov pair embedded on PMA is found to be the active site, not only for the formation of N2O2* by the reaction of two NO molecule via Eley–Rideal pathway but for the decomposition of N2O to form N2; (4) the adsorption of NO molecule on the Cu–Ov pair with a bridging model result in a charge transfer from Cu atom to π* antibonding orbital of NO molecule; (5) IR spectroscopy of the key intermediates have been identified based on our DFT calculations; (6) the Cu atom servers as an electron acceptor in Ov formation steps and an electron donor in N2O2 decomposition steps, and thus represented an electron reservoir. These results suggest that the POM–supported SACs with cheaper Cu element is an efficient catalyst for the catalyst of the reaction between CO and NO .

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Publication details

The article was received on 24 Feb 2019, accepted on 16 Apr 2019 and first published on 16 Apr 2019


Article type: Paper
DOI: 10.1039/C9CP01092K
Citation: Phys. Chem. Chem. Phys., 2019, Accepted Manuscript

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    Calculations of NO Reduction with CO over a Cu1/PMA Single–Atom Catalyst: A Study of Surface Oxygen Species, Active Sites, and Reaction Mechanism

    C. Liu, C. Sun, M. Jiang, L. Zhang and M. Sun, Phys. Chem. Chem. Phys., 2019, Accepted Manuscript , DOI: 10.1039/C9CP01092K

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