Tuning Interfacial Water Friction through Moiré Twist

Abstract: Nanofluidics is pivotal in fundamental research and diverse applications, from water desalination to energy harvesting and biological analysis. Dynamically manipulating nanofluidic properties, such as diffusion and friction, presents an avenue for advancement in this field. Twisted bilayer graphene, particularly at the magic angle, has garnered attention for its unconventional superconductivity and correlated insulator behavior due to strong electronic correlations. However, the impact of the electronic properties of moir\'e patterns in twisted bilayer graphene on structural and dynamic properties of water remains largely unexplored. Computational challenges, stemming from simulating large unit cells using density functional theory, have hindered progress. This study addresses this gap by investigating water behavior on twisted bilayer graphene, employing a deep neural network potential (DP) model trained with a dataset from ab initio molecular dynamics simulations. It is found that as the twisted angle approaches the magic angle, interfacial water friction increases, leading to reduced water diffusion. Notably, the analysis shows that at smaller twisted angles with larger moir\'e patterns, water is more likely to reside in AA stacking regions than AB (or BA) stacking regions, a distinction that diminishes with smaller moir\'e patterns. This exploration illustrates the potential for leveraging the distinctive properties of twisted bilayer graphene to effectively control and optimize nanofluidic behavior.