Catalytic Reduction of N<sub>2</sub>O by CO on Single-Atom Catalysts Au/C<sub>2</sub>N and Cu/C<sub>2</sub>N: A First-Principles Study
oleh: Shengyang Su, Junmei Ma, Zhenhua Liu, Domoina Holiharimanana, Hao Sun
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2023-03-01 |
Deskripsi
The catalytic conversion of greenhouse gases, such as N<sub>2</sub>O, is a promising way to mitigate global warming. In this work, density functional theory (DFT) studies were performed to study N<sub>2</sub>O reduction by CO over single-atom catalysts (SACs) and compare the performance of noble (Au/C<sub>2</sub>N) and non-noble (Cu/C<sub>2</sub>N) SACs. The computational results indicated that catalytic N<sub>2</sub>O reduction on both catalysts occurs via two mechanisms: (I) the N<sub>2</sub>O adsorption mechanism—starting from the adsorption on the catalysts, N<sub>2</sub>O decomposes to a N<sub>2</sub> molecule and O-M/C<sub>2</sub>N intermediate, and then CO reacts with O atom on the O-M/C<sub>2</sub>N intermediate to form CO<sub>2</sub>; and (II) the CO adsorption mechanism—CO and N<sub>2</sub>O are adsorbed on the catalyst successively, and then a synergistic reaction occurs to produce N<sub>2</sub> and CO<sub>2</sub> directly. The computational results show that mechanism I exhibits an obvious superiority over mechanism II for both catalysts due to the lower activation enthalpy. The activation enthalpies of the rate-determining step in mechanism I are 1.10 and 1.26 eV on Au/C<sub>2</sub>N and Cu/C<sub>2</sub>N, respectively. These results imply that Cu/C<sub>2</sub>N, an abundant-earth SAC, can be as active as expensive Au/C<sub>2</sub>N. Herein, our research provides a theoretical foundation for the catalytic reduction of N<sub>2</sub>O and broadens the application of non-noble-metal SACs.