Metallic molybdenum disulphide nanosheet-based electrochemical actuators

Title	Metallic molybdenum disulphide nanosheet-based electrochemical actuators
Authors	Muharrem Acerce,E. Koray Akdoğan,Manish Chhowalla
Magazine	Nature
Date	08/30/2017
DOI	10.1038/nature23668
Introduction	Actuators, which convert electrical energy into mechanical motion, are vital components across numerous electromechanical systems and robotics. Their applications span from steerable catheters and adaptive aircraft wings to drag-reducing wind turbines. Such actuation systems can operate through diverse mechanisms, including thermal changes, solvent interactions, or electrochemical processes, as seen in carbon nanotube, graphite, polymer, and metal electrodes. This work presents the development of electrode films from chemically exfoliated nanosheets of two-dimensional metallic molybdenum disulfide (MoS2), restacked onto thin plastic substrates. These films exhibit dynamic expansion and contraction, generating significant mechanical forces. They can lift loads exceeding 150 times their own weight over several millimetres and sustain hundreds of operational cycles. The MoS2 films achieve mechanical stresses of approximately 17 megapascals, surpassing mammalian muscle (0.3 megapascals) and approaching ceramic piezoelectric actuators (40 megapascals), with strains of about 0.6 percent at frequencies up to 1 hertz. This impressive actuation performance stems from the high electrical conductivity of the metallic 1T phase of MoS2 nanosheets, the elastic modulus of the restacked MoS2 layers (2 to 4 gigapascals), and efficient proton diffusion within the nanosheet layers. These findings open avenues for advanced electrochemical actuators suitable for high-strain and high-frequency applications.
Quote	Muharrem Acerce, E. Koray Akdoğan and Manish Chhowalla. Metallic molybdenum disulfide nanosheet-based electrochemical actuators. Nature. 2017. DOI: 10.1038/nature23668
Element	Molybdenum (Mo) , Sulfur (S) , Carbon (C) , Hydrogen (H)
Materials	Chemical Compounds , Metals and Alloys
Topics	Smart and Functional Materials
Industry	Aerospace , Medical Devices , Electronics , Research & Laboratory