First-principles insights into the role of edges in the binding mechanisms of Au4 clusters on MoSe2 nanoflakes

An atomistic understanding of the interaction between Au clusters and dichalcogenides nanoflakes of different polytypes is fundamental to improve our knowledge to the tuning of the physical-chemical properties of hybrid dimensional composite materials. Here, we report a density functional theory investigation into the changes of structural, energetic, and electronic properties induced by the adsorption of Au-4 clusters (planar and tetrahedron) onto Mo16Se32 and Mo36Se72 nanoflakes of both 1T' and 2H polytypes. We found that the Au-Se interaction plays a critical role in the nature of the Au-4/MoSe2 interactions, in which there is a strong energetic preference for the S atoms located at the edges for all nanoflake sizes and polytypes. In summary, the Au...MoSe2 binding mechanisms is composed of either (i) splitting of Se sp(2)-orbitals interacting with Au sd(3)-orbitals, or (ii) re-hybridized Au sd(3) splitting of Mo d(z)(2)-orbitals, with low charge transfer in both due to Au-4 cluster electron filling. Furthermore, the cluster/nanoflake adsorption energetics and structural distortions due to the Au...MoSe2 interactions are mainly determined by the MoSe2 edge configurations.