Electronic-Friction-Modulated Water Slip at MoS2-Based van der Waals Heterostructures–Water Interfaces

Friction is a key determinant governing energy dissipation at solid–water interfaces, but the interfacial friction mechanism remains poorly understood. Herein, we systematically investigated water slip in MoS2/(WS2, hBN, and graphene) van der Waals heterostructures (vdWHs) with MoS2 as the top layer. The water slip length increases from 9.6 nm on MoS2/WS2 to 12.8 nm on MoS2/hBN and reaches 36.7 nm on MoS2/graphene based on atomic force microscopy. Photoluminescence and Raman spectroscopy reveal charge transfer from vdWHs to water that strongly correlates with the water slip length. Simulations indicate that electron transfer from MoS2/WS2 to water enhances charge density at vdWHs–water interfaces, hindering water slip. In contrast, slight hole injection from MoS2/(hBN and graphene) into water reduces the residual interfacial charge, promoting water slip. Our findings elucidate friction mechanisms from the perspective of interfacial electronic friction, providing novel insights into energy transfer at vdWHs–water interfaces and a foundation for the design of advanced nanofluidic devices.