Formation and Characterization of Heterostructures with Moiré Patterns Through Deposition and Sintering of Bimetallic Gold-Platinum Group Metal Nanoparticles on MoS₂

Transition metal dichalcogenides (TMDs), such as MoS₂ 2D films, can be combined with a layer of metals to form heterostructures with unique electronic, plasmonic, and optical properties. This class of heterostructures is rapidly expanding, with a constant push to design innovative combinations and understand the structure-property correlations. In this work, we designed heterostructures of MoS₂/Au-platinum group metals (PGMs) by deposition and sintering of free-standing bimetallic nanoparticles on MoS₂ 2D films. We developed a process to remove carbon contamination on the sample thermally, then found that the sintering of nanoparticles forms flat bimetallic islands on the surface of MoS₂. The size and composition of the bimetallic nanoparticles was tuned to control the morphology of the resulting islands formed after sintering. Gold and PGMs (Ru, Rh, or Ir) remained segregated, and the metals formed moiré patterns showing the crystallinity and orientation relationship between the metals and MoS₂, after annealing at high temperatures. We used <i>in situ</i> gas-heating aberration-corrected advanced transmission electron microscopy to understand the formation, stability, and properties of these heterostructures. We also showed complex interfaces between phases (Au, PGMs, and MoS₂) that could be beneficial for precise tuning of physical properties. This work outlines a possible pathway to form heterostructures that combine MoS₂ with metallic islands to expand the range of available combinations through unique interface engineering.