Mechanisms in the Catalytic Reduction of N 2 O by CO over the M 13 @Cu 42 Clusters of Aromatic-like Inorganic and Metal Compounds.

Metal aromatic substances play a unique and important role in both experimental and theoretical aspects, and they have made tremendous progress in the past few decades. The new aromaticity system has posed a significant challenge and expansion to the concept of aromaticity. From this perspective, based on spin-polarized density functional theory (DFT) calculations, we systematically investigated the doping effects on the reduction reactions of N 2 O catalyzed by CO for M 13 @Cu 42 (M = Cu, Co, Ni, Zn, Ru, Rh, Pd, Pt) core-shell clusters from aromatic-like inorganic and metal compounds. It was found that compared with the pure Cu 55 cluster, the strong M-Cu bonds provide more structural stability for M 13 @Cu 42 clusters. Electrons that transferred from the M 13 @Cu 42 to N 2 O promoted the activation and dissociation of the N-O bond. Two possible reaction modes of co-adsorption (L-H) and stepwise adsorption (E-R) mechanisms over M 13 @Cu 42 clusters were thoroughly discovered. The results showed that the exothermic phenomenon was accompanied with the decomposition process of N 2 O via L-H mechanisms for all of the considered M 13 @Cu 42 clusters and via E-R mechanisms for most of the M 13 @Cu 42 clusters. Furthermore, the rate-limiting step of the whole reactions for the M 13 @Cu 42 clusters were examined as the CO oxidation process. Our numerical calculations suggested that the Ni 13 @Cu 42 cluster and Co 13 @Cu 42 clusters exhibited superior potential in the reduction reactions of N 2 O by CO; especially, Ni 13 @Cu 42 clusters are highly active, with very low free energy barriers of 9.68 kcal/mol under the L-H mechanism. This work demonstrates that the transition metal core encapsulated M 13 @Cu 42 clusters can present superior catalytic activities towards N 2 O reduction by CO.