Graphene-like Materials

Graphene-like Materials List

Graphene is a new class of two-dimensional layered compound. With the unique properties, graphene has been widely applied in many fields. Inspired by the excellent structure of graphene, graphene-like materials have been developed. Graphene-like materials are a class of two-dimensional crystal materials, and they can be composed of a single layer or several atomic layers, which are linked by van der Waals forces. Due to the linked mode, the electrons of graphene-like materials can only move freely on the non-nanoscale of two dimensions.

Applications:

Graphene-like materials are a new type of nanomaterials with unique physical and chemical properties and have important applications in many fields.

• Secondary batteries field: As an important clean energy source, secondary batteries can be used to reactivate the active substances by charging, and the main types of secondary batteries are lithium ion and magnesium ion secondary batteries. In addition, the secondary batteries also have the advantages of low cost, low pollution and large capacity. Lithium and magnesium ions can be effectively inserted into graphene-like materials. Therefore, graphene-like materials can be used as anode materials for lithium ion batteries and magnesium ion batteries.
• Field effect transistor field: Field effect transistor is one of the most important devices in modern microelectronics technology, which can affect the conductivity of semiconductor materials by changing the electric field. Graphene-like materials are direct bandgap semiconductors, so they can be used to make field effect transistors with large switching current ratio, high carrier mobility and low energy consumption.

Figure 1. An example of field effect transistor based on graphene-like materials.

• Sensor field: With the unique electronic properties, large specific surface area and two-dimensional layered structure, graphene-like materials are conducive to the adsorption of gas molecules, so they have a promising application prospect in gas sensors. Moreover, the gas sensors based on graphene-like materials have the advantages of good stability and high sensitivity. In addition, graphene-like materials can also be used as light sensors.
• The others: Graphene-like materials can also be used in organic light emitting diodes, memory field and the others. For example, organic light emitting diode made of graphene-like materials has the advantages of spontaneous light, wide viewing angle, low energy consumption, full color, and the others, which has broad application prospects in the fields of flat panel display and solid-state lighting.

Classification:

There are many types of graphene-like materials, which can be classified according to their composition.

• Molybdenum disulfide: Molybdenum disulfide is a two-dimensional crystal material with sandwich structure, which is composed of monolayer or multilayer molybdenum disulfide. Monolayer molybdenum disulfide is composed of three atomic layers. The middle layer is molybdenum atomic layer, and the upper and lower layers are sulfur atomic layers. The molybdenum atomic layer is sandwiched between two sulfur atomic layers to form a kind of "sandwich" structure. Molybdenum atoms and sulfur atoms are covalently bonded to form two-dimensional atomic crystals. Multilayer molybdenum disulfide is composed of several monolayer molybdenum disulfide, and the number of layers is less than five. Moreover, there is weak van der Waals force between the layers.

Figure 2. The structure of molybdenum disulfide.

• Black phosphorus: Black phosphorus is a thermodynamically stable phosphorus allotrope with orthogonal structure. Black phosphorus has a wavy layered structure similar to that of graphene and is easy to be peeled into single or less layers of nanosheets. Black phosphorus is a natural P-type direct band gap semiconductor. The band gap of black phosphorus can be regulated by the number of layers. Moreover, it has obvious anisotropy and high electron mobility.
• The others: There are many other graphene-like materials, including MoSe₂, WSe₂, MoSe₂, Bi₂Te₃, SnSe₂, hexagonal boron nitride crystals, coronene, muscovite and the others.

References

1. Wachter S, Polyushkin D K, Bethge O, et al. A microprocessor based on a two-dimensional semiconductor[J]. Nature Communications, 2017, 8:14948.
2. Ming-Hong W, Lin L, Ning L, et al. Molybdenum disulfide (MoS2) as a co-catalyst for photocatalytic degradation of organic contaminants: A review[J]. Process Safety & Environmental Protection, 2018.