Attraction and Actuation of Water Nanodroplets on MoS2/MoSe2 Lateral Heterostructure Films

Abstract

Investigating the behavior, manipulation and transport of nanodroplets on surface of solid film is critical for optimizing functions of films and advancing diverse high-value applications across multiple fields. By using molecular dynamics simulations, we mainly investigate the moving behavior of water nanodroplets on the surface of MoS2/MoSe2 lateral heterostructure films. The results indicate that MoS2 exhibits more hydrophobic property than MoSe2 membrane, confirmed by the observation of a larger contact angle on MoSe2 membrane. The van der Waals interactions were found to mainly dominate the wettability difference between MoS₂ and MoSe₂, where MoSe₂ demonstrating a significantly stronger adsorption capacity for nanodroplets than that of MoS₂. Based on this wettability difference, MoS₂/MoSe₂ lateral heterostructure films were designed to realize the directional migration, enrichment, and immobilization of water nanodroplets sequentially. Besides, the effective regulation of moving speed and direction of nanodroplets were achieved by constructing a MoS₂/MoSe₂ lateral heterostructure film with a wettability gradient. This research provides a theoretical basis and design insights for the development of microfluidic devices and droplet manipulation systems based on lateral heterostructures using two-dimensional transition metal chalcogenide materials.