Emerging versatile two-dimensional MoSi$_2$N$_4$ family

TL;DR

This paper reviews the recent progress and potential applications of the emerging 2D MoSi$_2$N$_4$ family, highlighting their unique structures, versatile properties, and tunability for various technological uses.

Contribution

It provides a comprehensive overview of the structural, physical, and application-related advancements in the 2D MA$_2$Z$_4$ family, emphasizing their versatility and future prospects.

Findings

Unique sandwich structure of monolayer MA$_2$Z$_4$

Versatile properties including mechanics, piezoelectricity, and magnetism

Potential applications in transistors, photocatalysts, batteries, and sensors

Abstract

The discovery of two-dimensional (2D) layered MoSi$_2$N$_4$ and WSi$_2$N$_4$ without knowing their 3D parents by chemical vapor deposition in 2020 has stimulated extensive studies of 2D MA$_2$Z$_4$ system due to its structural complexity and diversity as well as versatile and intriguing properties. Here, a comprehensive overview on the state-of-the-art progress of this 2D MA$_2$Z$_4$ family is presented. Starting by describing the unique sandwich structural characteristics of the emerging monolayer MA$_2$Z$_4$, we summarize and anatomize their versatile properties including mechanics, piezoelectricity, thermal transport, electronics, optics/optoelectronics, and magnetism. The property tunability via strain engineering, surface functionalization and layered strategy is also elaborated. Theoretical and experimental attempts or advances in applying 2D MA$_2$Z$_4$ to transistors, photocatalysts, batteries and gas sensors are then reviewed to show its prospective applications over a vast territory. We further discuss new opportunities and suggest prospects for this emerging 2D family. The overview is anticipated to guide the further understanding and exploration on 2D MA$_2$Z$_4$.