First-Principles Study on the Single Ir Atom Embedded Graphdiyne: An Efficient Catalyst for CO Oxidation

Single-atom catalysts have attracted wide attention due to the maximum usage of single atom and the great potential to achieve high activity and selectivity. The oxidation of CO molecules on the single Ir atom embedded graphdiyne (Ir-GDY) has been investigated by using the first-principles calculations. A variety of reaction mechanisms are taken into account and a new pathway is found to catalyze CO oxidation more efficiently on Ir-GDY. A comparison of the reaction energy barrier shows that the CO oxidation likely occurs in the new Eley-Rideal (NER) mechanism rather than the traditional mechanism. In the NER mechanism, the adsorbed O-2 molecule is activated by two physisorbed CO molecules thereby formed two CO2 synchronously with the energy barrier of 0.37 eV, as the rate-limiting step. In this reaction, the electrons are transferred' from the substrateto the O-2 and CO, which promotes the decomposition of O-2. After the C-C bond cleavage, the OOCCOO intermediate dissociates to form two CO2 molecules, in which the electrons return to the substrate and then start a new round of oxidation. We also found that the Langmuir-Hinshelwood (0.77 eV) and termolecular Eley-Rideal (0.70 eV) mechanisms are also likely to proceed. Therefore, the Ir-GDY is an efficient catalysis for CO oxidation.