Molecular-Level Understanding of Water Transport Mechanisms in Functionalized Ti₃C₂T<i>_X</i> MXene Membrane-Combined Experimental Approaches

The hydrophilicity of two-dimensional (2D) transition-metal carbides, carbonitrides, and nitrides (MXene) nanochannels plays a critical role in water transport during filtration, yet its specific effects on MXene membranes remain inadequately understood. Herein, we systematically investigated water transport through Ti₃C₂T<i>_X</i> MXene nanochannels using molecular dynamics simulations coupled with experimental validation, addressing a significant knowledge gap in MXene-based separation membranes. Our simulations demonstrated that strong interactions between water molecules and hydrophilic nanochannel MXene surfaces (Ti₃C₂(OH)₂ MXene or Ti₃C₂(NH)₂ MXene) facilitated the formation of ordered molecular arrangements, substantially improving water permeability. Conversely, hydrophobic nanochannels (Ti₃C₂O₂ MXene or Ti₃C₂F₂ MXene) exhibited disordered water molecule distributions, leading to reduced permeability. Experimental validation corroborated these simulation results, demonstrating a direct correlation between the hydrophilicity of the Ti₃C₂T<i>_X</i> surface and the water flux. The highly hydrophilic Ti₃C₂(OH)₂ MXenes exhibited water flux maximum, whereas the more hydrophobic Ti₃C₂F₂ MXenes had the lowest water flux. By integrating molecular dynamics simulations with experimental analyses, we gained comprehensive insights into the influence of nanochannel hydrophilicity on water transport mechanisms in MXene membranes. These findings provide critical guidelines for designing high-performance MXene-based membranes for advanced water treatment and separation applications.