Introductory Chapter: 2D Materials

*Yotsarayuth Seekaew and Chatchawal Wongchoosuk*

### **1. Overview**

Two-dimensional (2D) materials are a class of nanomaterials that have two dimensions (XY plane) outside of the nanometric size range and atomic-scale thicknesses (Z dimension). The first well-known 2D material is graphene consisting of a single layer of carbon atoms arranged in a hexagonal lattice. To compare with 0D material (fullerene) and 1D material (carbon nanotube), the researches related to 2D material (graphene) have grown up quickly over other carbon allotropes as shown in **Figure 1**. Based on Scopus database (search by keyword "graphene" on March 18, 2019), publications on graphene increased from 3772 papers in 2010 to 21,439 papers in 2018. The total number of graphene-related publications is 132,628 documents. However, it is not only 2D graphene that has been widely applied in a large variety of potential applications but also other 2D materials such as tungsten disulfide, molybdenum disulfide, and silicon nitride open up new opportunities for the future devices. In this chapter, synthesis and applications of these 2D materials have been introduced and presented in brief.

#### **Figure 1.**

*Number of publications versus publication years based on Scopus database (search by keyword "fullerene," "carbon nanotube," and "graphene" on March 18, 2019).*
