Interactions at heterointerfaces influence actuation in wet cast 1T-MoS2 and V2O5·0.5H2O thin films†

Abstract

Interfacial interaction strengths are often invoked as determining factors in the chemomechanical coupling across actuating lamellar structures. However, electrochemical layered actuators of 100 nanometers to a few microns in thickness are often well described with classical models which depend only on bulk elastic moduli and relative thicknesses. We report a set of electrochemical systems composed of flexible working electrodes based on sub-micron thin films of 1T-MoS₂ and V₂O₅·0.5H₂O deposited onto metallic Au and Ni surfaces. Changes in electrode curvature were measured as a function of applied potential from which induced strains and stresses were calculated using a Timoshenko multi-layer beam bending model. The 1T-MoS₂ system achieved a maximum actuation strain of 0.57(5)% and 1.29(13)% while the V₂O₅·0.5H₂O system achieved 1.17(8)% and 1.2(2)% on Ni and Au respectively. Based on these results, small differences in interfacial interactions, such as in the case of the V₂O₅·0.5H₂O, were not distinguishable, whereas for very thin films of 1T-MoS₂, where strong differences between Au–S and Ni–S were present, the strong Au–S interaction resulted in greater actuation strains.