Interaction of Ethylene with Ir(n) (n = 1–10): From Bare Clusters to γ-Al(2)O(3)-Supported Nanoparticles

Comprehending the bond nature of ethylene-metal clusters at the atomic level is important for the design of nanocatalysts and their applications in the fields of fine chemistry and petroleum refining. The growth of Ir(n) (n = 1–10) on γ–Al(2)O(3)(110) and ethylene adsorption on bare and γ–Al(2)O(3)(110)-supported Ir(n) (n = 1–10) clusters were investigated using the density functional theory (DFT) approach. The mode stability of ethylene adsorption on the bare Ir(n) clusters followed the order π > di-σ > B-T, with the exception of Ir(8) where the π structure was less stable than the di-σ configuration. On supported Ir(n) (n = 4–7 and 10) the stability sequence was π > di-σ > di-σ′ (at interface), while on supported Ir(n) (n = 2, 3, 8, and 9) the sequence changed to di-σ > π > di-σ′ (at interface). Two-thirds of ethylene adsorption on the supported Ir(n) clusters were weaker than its adsorption on the bare Ir(n) clusters. The pre-adsorbed ethylene at the interface was found to facilitate the nucleation from the even-sized supported Ir(n) to odd-sized Ir(n) clusters, but hindered the nucleation from the odd-sized Ir(n) to even-sized Ir(n) clusters.