Atomistic Simulation of Ion Transport in Atomic Stacking Titania Membranes: Understanding Defect–Selectivity Correlation

Shao-Ning Hsu^1*, Po-Yu Yang¹, Chun-Wei Pao¹

¹Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

* Presenter:Shao-Ning Hsu, email:s10455334@gmail.com

The emerging field of iontronics holds great promise for next-generation energy technologies by enabling precise control of ionic transport through angstrom-scale channels. Two-dimensional atomic stacking membranes, particularly titania-based nanosheets, provide highly ordered lamellar structures that allow selective ion transport, making them attractive for applications such as iontronic devices, energy conversion, and osmotic power generation. Despite recent experimental demonstrations of high cation selectivity in these atomic stacking 2D membranes, the underlying mechanisms that govern ion transport, especially the role of intrinsic defects, remain poorly understood.

In this work, we employ atomistic molecular dynamics simulations to investigate ion transport behavior in atomic stacking titania membranes. Our study specifically focuses on how titanium vacancies affect cation selectivity and the distribution of interfacial electric fields within sub-nanometer channels. By combining grand canonical Monte Carlo (GCMC) simulations with steered molecular dynamics (SMD), we model the adsorption, migration, and partial dehydration of K⁺ and Cl⁻ ions under realistic confinement conditions. Preliminary results suggest that defects can locally modulate the electrostatic environment, influencing both the energy barrier and preferential pathways for cation transport.

These atomistic insights provide a deeper understanding of the defect–selectivity correlation in 2D ionic channels, offering guidance for rational design of membranes with tunable ion transport properties. Such knowledge is crucial for advancing iontronic devices and energy-conversion systems, where precise ionic control at the atomic scale can significantly enhance device performance, stability, and efficiency.

Keywords: Iontronics, Two-Dimensional Materials, Titania Membranes, Defect Engineering, Ion Transport