What determines the water wettability and permeability of Ti3C2Tx MXene thin films?

LY Feng and S Luo and RH Zhou and QH Fang and H Wu and B Liu, JOURNAL OF MEMBRANE SCIENCE, 721, 123786 (2025).

DOI: 10.1016/j.memsci.2025.123786

Ti3C2Tx MXene, a two-dimensional metal carbide, has emerged as a promising membrane material for various energy and environment applications. Its high hydrophilicity is widely acknowledged and commonly attributed to its surface functional groups that confer a significant surface charge. Nonetheless, the water wettability measurements of Ti3C2Tx MXene thin films vary considerably across studies. This inconsistency raises a key question: What governs the wettability of Ti3C2Tx MXene? To answer this, we performed a combination of experimental assessments and molecular dynamics (MD) simulations to explore the water wettability and permeability of Ti3C2Tx MXene films. We modified their surface chemistry by adjusting the number of surface -OH groups through vacuum annealing and alkaline solution treatments. A reduction in -OH groups decreased both wettabilitys and permeability, while an increase in -OH groups enhanced these properties. MD simulations indicated that hydrogen bonding at the water-MXene interface is the main factor affecting wettability and permeability. Although an increase in -OH groups promotes hydrogen bonding, wettability does not have a monotonic relationship with the -OH group density. Notably, in the absence of -OH groups, water flow within MXene nanochannels exhibits boundary slippage, even when the channel walls retain slight hydrophilicity. This slippage leads to significantly higher water permeability for the Ti3C2O2 thin film compared to Ti3C2(OH)2, yet remains considerably lower than that of graphene films due to the presence of interfacial hydrogen bonds. The findings of this study have significantly advanced our comprehension of Ti3C2Tx MXene's wettability, which is instrumental for optimizing its functional design.

Return to Publications page