Electric-Field-Induced Instability of Redox-Exfoliated Layered Transition Metal Dichalcogenides

Redox-exfoliated layered transition metal dichalcogenides (LTMDs) find many applications in nonlinear optics, displays, and electronics. The investigated redox LTMD suspensions in this work were characterized optically and found to be highly stable due to surface anionic polyoxometalates (POMs), which maintained the separation between sheets by Coulombic repulsion. However, exposure of the uniform suspensions of LTMDs to an electric field led to agglomeration of the TMDs into clumps of the material in a nearly transparent solvent. This was attributed to the electrochemical reduction of the surface anionic POMs. The electrochemical stability of the redox-exfoliated ACN-MoS2 samples was also investigated by cyclic voltammetric measurements, which confirmed the POM reduction process. This study highlights that the stability of the LTMD/POM system can be compromised by the application of a low-intensity electric field and has bearings on its reliability in optoelectronic devices.