Adsorption‐Free Growth of Ultra‐Thin Molybdenum Membranes with a Low‐Symmetry Rectangular Lattice Structure

Abstract

Although low‐symmetry lattice structure of 2D transition metals is highly anticipated for both fundamental research and potentially distinctive application, it still has not been experimentally realized, which greatly hinders the exploration of the unique properties. Here, ultra‐thin body‐centered‐cubic (bcc) phase molybdenum (Mo) membranes are successfully synthesized with a low‐symmetry rectangular (110) crystal face via an adsorption‐free reaction. Through experimental and density functional theory studies, no foreign atoms being adsorbed is shown to be a key factor for the successful preparation of the bcc phase 2D transition metal with (110) faces. The realization of 2D Mo(110) with a low‐symmetric rectangular lattice structure extends the scope of 2D structures and is also beneficial for the exploration and development of low‐symmetry rectangular lattice‐structured materials with unique properties.

Growth of 2D MoP single crystals on liquid metals by chemical vapor deposition

“…Researches in two-dimensional (2D) materials have increasingly grown triggered by pioneering studies on graphene [1][2][3][4]. As an emerging family of 2D materials, 2D transition metal phosphides (TMPs) are predicted with novel properties, which are appealing for many applications, including optical, thermal insulating materials, magnetic material and catalysts [5,6].…”

In Situ Fabrication of Freestanding Single‐Atom‐Thick 2D Metal/Metallene and 2D Metal/ Metallene Oxide Membranes: Recent Developments

“…The development of controllable methods for tuning the properties of 2D materials by either reducing their size or creating new nanostructured materials is pivotal to the realization of nextgeneration functional devices. Si et al [43] used an aberrationcorrected TEM system operating at voltages higher than 80 kV to preferentially remove C from 2D 𝛼-Mo 2 C crystals. The irradiation process led to the formation of thin rectangular Mo structures with lattice parameters of 0.233 and 0.167 nm, as shown in Figure 6n and having the (110) crystal orientation.…”

“…In addition, while in the case of other methods for synthesizing 2D metals/metal oxides, it may be challenging to demonstrate the freestanding structure of the synthesized material; this difficulty can be overcome using in‐situ (S)TEM ( Figure 1 ) and graphene pores as templates [ 19 , 24 , 36 , 37 , 38 , 39 , 40 ] or e‐beam‐based thinning methods. [ 41 , 42 , 43 , 44 ] In this review, we summarize the recent progress made in the in situ e‐beam‐driven synthesis of freestanding 2D metal/metal oxide membranes using(S)TEM and highlight the importance of in situ (S)TEM in the development of freestanding 2D materials.…”

Elemental 2D Materials: Progress and Perspectives Toward Unconventional Structures

“…Recently, our group revealed that ultrathin Mo membranes with a low‐symmetric rectangular (110) crystal face could be synthesized successfully by an adsorption‐free reaction (Figure 6e). [ 17 ] It is the first time that the low‐symmetry lattice structure of 2D transition metals has been experimentally realized, although the rectangular lattice structure exists some transition metals crystal faces. Image simulations verify that the obtained rectangular lattice structure is AB stacked Mo(110) with even atom thickness (2, 4, etc.…”

“…Hitherto, many researchers have made tremendous efforts to synthesize elemental 2D materials with unconventional structures and developed a series of strategies, including surface modification, epitaxial growth, electron beam irradiation, crystal inhibition, and high pressure. [ 13–18 ] However, present scientific achievements and systematic understanding of effective synthetic strategies have not been presented yet. It is highly demanded to give a clear guideline of the different strategies for controlling the preparation and reasonable design of unconventional structures of elemental 2D materials.…”