Study of the Growth Mechanism of Solution-Synthesized Symmetric Tellurium Nanoflakes at Atomic Resolution

As a new member of 2D materials, 2D tellurium (Te) has recently attracted much attention due to its intriguing properties. Through hydrothermal processing, 2D Te with tunable thickness and size has been realized, and its growth mechanism has also been studied. However, the tailored growth of 2D Te nanoflakes with symmetrical morphologies and interfacial moiré fringes has never been reported. Here, 2D Te nanoflakes have been prepared using the hydrothermal method, and mirror-symmetrical shapes (including "V-shape," "heart-shape," and "paper airplane-shape") with obvious moiré fringes in the middle of the nanoflakes are observed. Comprehensive transmission electron microscopy (TEM) techniques are utilized for structural characterization of these nanoflakes, especially the moiré fringes in the symmetry axis region of the nanoflakes. The systematic analyses of the moiré fringes and the observation of obvious overlapping edges of the composing nanoflakes from the cross-sectional samples reveal the possible mechanism of morphological evolution for these symmetrical nanoflakes. These details may fill the research gap in the controllable growth of 2D Te nanomaterials, pave the way for the fabrication of 2D Te moiré superlattices and in-plane homojunctions, and promote their future versatile applications.