Two-dimensional MoS$_2$ electromechanical actuators

TL;DR

This study uses density functional theory to analyze the electromechanical properties of monolayer MoS$_2$ in different structures, revealing their potential for use in electromechanical actuators due to their strain and work density capabilities.

Contribution

It provides a detailed comparison of the electromechanical responses of 1H, 1T, and 1T$^ extprime$ MoS$_2$ monolayers under charge doping, highlighting their suitability for actuator applications.

Findings

1T and 1T$^ extprime$ structures exhibit better performance than 1H.

Charge doping induces reversible strain from -0.68% to 2.67%.

Work density ranges from 4.4 to 36.9 MJ/m$^3$.

Abstract

We investigate electromechanical properties of two-dimensional MoS$_2$ monolayers in the 1H, 1T, and 1T$^\prime$ structures as a function of charge doping by using density functional theory. We find isotropic elastic moduli in the 1H and 1T structures, while the 1T$^\prime$ structure exhibits an anisotropic elastic modulus. Moreover, the 1T structure is shown to have a negative Poisson's ratio, while Poisson's ratios of the 1H and 1T$^\prime$ are positive. By charge doping, the monolayer MoS$_2$ shows a reversibly strain and work density per cycle ranging from -0.68% to 2.67% and from 4.4 to 36.9 MJ/m$^3$, respectively, making them suitable for applications in electromechanical actuators. Stress generated is also examined in this work and we find that 1T and 1T$^\prime$ MoS$_2$ monolayers relatively have better performance than 1H MoS$_2$ monolayer. We argue that such excellent electromechanical performance originate from the electrical conductivity of the metallic 1T and semimetallic 1T$^\prime$ structures high Young's modulus of about $150-200$ GPa.