Theoretical Insights into MXene Termination and Surface Charge Regulation
Xuepeng Wang, Gary M. C. Ong, Michael Naguib, Jianzhong Wu
Abstract
MXenes are two-dimensional materials promising for diverse applications ranging from electrical energy storage to biomedical devices. Whereas the importance of surface termination on MXene performance has been well documented, understanding the surface structure and its variation with the environment has been a fundamental challenge from both theoretical and experimental perspectives. Herein, we propose complementary first-principles and micro-thermodynamic models to predict MXene structure, surface termination, and charge regulation in response to variations of solution conditions. While the first-principles calculations allow us to identify the atomic structure and the electronic behavior of the layered materials, the thermodynamic model provides useful quantitative description of the surface charge in terms of the electric potential and solution conditions. Together, the theoretical models offer a powerful computational platform to investigate the MXene termination and charging behavior under conditions of practical interest.