Six-membered-ring inorganic materials: definition and prospects

Abstract

The six-membered ring (SMR) is a common structure unit for numerous material systems. These materials include, but are not limited to, the typical two-dimensional materials such as graphene, h-BN, and transition metal dichalcogenides, as well as three-dimensional materials such as beryllium, magnesium, MgB2, and Bi2Se3. Although many of these materials have already become ‘stars’ in materials science and condensed-matter physics, little attention has been paid to the roles of their SMR unit across a wide range of compositions and structures. In this article, we systematically analyze these materials with respect to their very basic SMR structural unit, which has been found to play a deterministic role in the occurrence of many intriguing properties and phenomena, such as Dirac electronic and phononic spectra, superconductivity and topology. As a result, we have defined this group of materials as SMR inorganic materials, which opens a new perspective on materials research and development. With their unique properties, SMR materials deserve wide attention and in-depth investigation from materials design, new physical discoveries to target-wizard applications. It is expected that SMR materials will find niche applications in next-generation information technology, renewable energy, space, etc.

Intercalated architecture of MA2Z4 family layered van der Waals materials with emerging topological, magnetic and superconducting properties

“…Up to now, most of the discovered monolayer 2D materials have a thickness with n ≤ 7. Graphene and hexagonal boron nitride ( h -BN) monolayer are famous six-membered ring (SMR) materials 17 of n = 1, which have been a central topic for over a decade 18 – 26 . In the silicon counterpart of graphene, the hexagonal honeycomb tends to be buckled into a double-atomic layer structure, that is, n = 2 (see Fig.…”

“… a Top and side views of representative monolayers for n ≤ 7, all belonging to the SMR materials 17 . b Schematic illustration of the intercalation method that uses the structures of a MoS 2 -like monolayer (2 H - and 1 T phases) and those of an InSe-like monolayer ( α and β phases) to construct the structures of a MA 2 Z 4 monolayer.…”

Single-Atom-Anchored Two-Dimensional MoSi2N4 Monolayers for Efficient Electroreduction of CO2 to Formic Acid and Methane

“…To date, the thickness of n ≤ 7 is the limit of the practical synthesis of single-layer 2D materials. Monolayer graphene is one atom thick (n = 1) and has a six-membered ring (SMR) configuration, 17 which is widely used in CO 2 reduction. 18−28 The silicon counterpart of graphene (n = 2) has also shown great potential for CO 2 reduction.…”

“…To date, the thickness of n ≤ 7 is the limit of the practical synthesis of single-layer 2D materials. Monolayer graphene is one atom thick ( n = 1) and has a six-membered ring (SMR) configuration, which is widely used in CO 2 reduction. − The silicon counterpart of graphene ( n = 2) has also shown great potential for CO 2 reduction. , For n = 3, researchers focused on monolayer transition-metal sulfur compounds with SMR configurations. Especially, the reduction of CO 2 to methanol can be achieved with the MoS 2 -supported single Co atom catalyst .…”

Effect of carbon doping on the structure and superconductivity in AlB$_{2}$-type (Mo$_{0.96}$Ti$_{0.04}$)$_{0.8}$B$_{2}$

“…Transition metal diborides (TMDBs) have attracted a lot of attention over the past few decades due to their diverse properties [1][2][3], including high hardness and shear strength [4][5][6][7], excellent corrosion resistance [8,9], superior catalytic performance [10,11], notrivial band topology [12,13], high electrical conductivity and even superconductivity [14][15][16][17][18]. Among existing TMDBs, molybdenum diboride is unique in that it exists in both hexagonal AlB 2 -type and rhombohedral structures [19].…”