Stability and nucleation of Irn (n = 1–5) clusters on different γ-Al2O3 surfaces: A density functional theory study

•Irn (n=2–5n=2–5) adsorption preferentially occurs on γ-Al2O3(110) than on (100) surface.•(110) surface hydroxylation does not favor the adsorption of Ir clusters.•The nucleation of Irn is preferable on γ-Al2O3(110) rather than on (100) surface.•Surface hydroxylation is beneficial to the nucleation of Irn clusters.•The support is unfavorable for the nucleation of Irn and block the clustering.

Density functional theory (DFT) calculations with periodic slab models are employed to explore the stability and nucleation of Irn (n=1–5n=1–5) clusters on three surfaces, namely, dehydrated γ-Al2O3(100), dehydrated γ-Al2O3(110), and hydrated γ-Al2O3(110) surfaces. The results show that the adsorption and nucleation of Irn (n=1–5n=1–5) clusters preferentially occurs on the (110) surface than on the (100) surface. Moreover, (110) surface hydroxylation does not favor the adsorption of Ir clusters, while benefits the nucleation of Ir clusters. Meanwhile, the support can weaken the nucleation ability of Ir clusters and block the aggregation of clusters.