The heterostructure of transition metal nanocrystal on two-dimensional (2D) materials exhibits unique physical and chemical properties through various interfacial interactions. It has been established that the atomic structure and strain in the vicinity of the interface determine the band structure and phonon modes of the nanocrystal, regulating the optical and electrical properties of such heterostructures. Hence, metal-support interfacial engineering is a demonstrated approach to acquiring desired properties of the nanocrystals. However, Previous studies largely focus on the strain and atomic configurations of interfaces between the MoS2 basal plane (normally {0001}) and transition metal. Information on the

side facet of MoS2 nanosheets, which also plays a vital role in nano devices and catalysis, as support for transition metal nanocrystals are still lacking.

Recently, Prof. Rongming Wang explored the regulation of interface structure and strain on MoS2 supported Pt nanocrystals which were prepared by reducing ultrasonic dispersed potassium chloroplatinate. The Pt-MoS2 heterostructure interface was systematically and quantitatively studied by aberration corrected transmission electron microscopy.

According to the results, three types of Pt-MoS2 interfaces (namely pit, step, and terrace) with distinct atomic configurations were identified. The strain within the Pt nanocrystals is sensitive to the atomic configuration of the supporting MoS2, which regulates the size of the Pt nanocrystals, and in all cases, the strains in Pt nanocrystals as resulting from the metal-support interaction are largely within the first two atomic layers. These results provide insights on tuning of nanocrystal strain, paving the way for precise control of 2D semiconductor heterostructures.

Figure: Different Growth Sites of Pt on MoS2 Edge. (a - f) Typical HRTEM images of a Pt nanocrystal grown at pit (a), step (c) and terrace (e), and corresponding schematic diagram (b, d, f). The white dashed lines marked the interface between Pt nanocrystal and MoS2. (g) Violin plots of Pt nanocrystals size distribution at different growth sites on MoS2 edge. The red spots connected by red dashed lines represent the average size of Pt nanocrystal grown at each site.