Morphotaxy of Layered van der Waals Materials

Abstract

Layered van der Waals (vdW) materials have attracted significant attention due to their materials properties that can enhance diverse applications including next-generation computing, biomedical devices, and energy conversion and storage technologies. This class of materials is typically studied in the two-dimensional (2D) limit by growing them directly on bulk substrates or exfoliating them from parent layered crystals to obtain single or few layers that preserve the original bonding. However, these vdW materials can also function as a platform for obtaining additional phases of matter at the nanoscale. Here, we introduce and review a synthesis paradigm, morphotaxy, where low-dimensional materials are realized by using the shape of an initial nanoscale precursor to template growth or chemical conversion. Using morphotaxy, diverse non-vdW materials such as HfO2 or InF3 can be synthesized in ultrathin form by changing the composition but preserving the shape of the original 2D layered material. Morphotaxy can also enable diverse atomically precise heterojunctions and other exotic structures such as Janus materials. Using this morphotaxial approach, the family of low-dimensional materials can be substantially expanded, thus creating vast possibilities for future fundamental studies and applied technologies.

Ni-Based Janus Pentagonal Monolayers as Promising Water-Splitting Photocatalysts

“…Janus structures can be synthesized by atom exchange or functionalization of one side of the material . For instance, Janus MoSSe has been obtained via controllable sulfurization of the top selenium-atom layer of MoSe 2 at 800 °C, or selenization of the top layer of MoS 2 .…”

“…Janus structures can be synthesized by atom exchange or functionalization of one side of the material. 52 For instance, Janus MoSSe has been obtained via controllable sulfurization of the top selenium-atom layer of MoSe 2 at 800 °C, 30 or selenization of the top layer of MoS 2 . 29 A similar technique can be used to obtain J-NiSSe, for example, by selenizing one side of the NiS 2 monolayer obtained via mechanical or chemical exfoliation.…”

Helical Bilayer Nanographenes: Impact of the Helicene Length on the Structural, Electrochemical, Photophysical, and Chiroptical Properties

“…Chemically, the pristine forms of these materials show strong in-plane covalent bonds and weak out-of-plane van der Waals (vdW) interactions. The stacking of several layers generates pseudocrystalline materials known as vdW layered solids . Remarkably, the twist angle between the layers of stacked 2D materials produces a moiré pattern, forming a superlattice with a new band structure that dramatically affects the electronic properties of the material .…”

Nature of Interlayer Bonds in Two-Dimensional Materials

“…Surprisingly, while 2D materials were systematized by chemical composition (for example monochalcogenides, dichalcogenides, MXenes) or by chemical composition in numerous reviews, differences in strength and types of interlayer bonds were not discussed and used for description of 2D 2 materials. [36][37][38][39][40] In this work we report a systematic study of the bonds length and strength as well as charge distribution in bulk and bilayer structures of several representative 2D systems such as graphene, hexagonal boron nitride (hBN), MoSe 2 , VSe 2 , and ditelureides (NiTe 2 , PdTe 2 , PtTe 2 ) by means of the first-principles calculations. Graphene and hBN have been chosen as classical examples of one-atom-thick crystals, MoSe 2 being the most studied material from dichalcogenides family, VSe 2 that represents another popular diselenides with 3d metal center and nonzero magnetic moment [41][42][43] and NiTe 2 , PdTe 2 , PtTe 2 as three ditelurides with the same morphology of the layer and metal center from the same group of the periodic table.…”

“…Results obtained in experimental studies , and theoretical simulations demonstrate a significant influence of the number and quality of subsurface layers on chemical activity of surface of fewlayer graphene systems and other 2D materials. − Another important example that evidences a significant role of the interlayer interactions is discrepancy between the chemical stability of the InSe monolayer and the chemical instability of the surface of the same compound in the bulk form. , Thus, unveiling the nature of noncovalent bonds between the neighboring layers is essential for understanding the physical and chemical properties of these structures and the further intelligent design of novel layered materials. Surprisingly, while 2D materials were systemized by chemical composition (for example, monochalcogenides, dichalcogenides, MXenes) or by chemical composition in numerous reviews, differences in strength and types of interlayer bonds were not discussed and used for the description of 2D materials. − …”