Attraction and actuation of water nanodroplets on MoS2/MoSe2 lateral heterostructure films

Abstract

Investigating the behavior, manipulation and transport of nanodroplets on the surface of solid films is critical for optimizing the functions of films and advancing diverse high-value applications across multiple fields. 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 properties than the MoSe₂ membrane, confirmed by the observation of a larger contact angle on the MoSe₂ membrane. The van der Waals interactions were found to mainly dominate the wettability difference between MoS₂ and MoSe₂, where MoSe₂ demonstrated a significantly stronger adsorption capacity for nanodroplets than 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, effective regulation of the moving speed and direction of nanodroplets was 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.