Interactions at heterointerfaces influence actuation in wet cast 1T-MoS2 and V2O5 ⋅ 0.5 H2O 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 in 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 · 0.5 H2O system achieved that of 1.17(8) % and 1.2(2) % on Ni and Au respectively. Based on these results, small differences in interfactional interactions such as in the case of the V2O5 · 0.5H2O were not distginguiable while for very thin films of 1T-MoS2 wher strong differences between Au-S and Ni-S were present the strong Au-S interaction resulted in greater actuation strain.