Assembly of 2D MXene nanosheets and TiO2 nanoparticles for fabricating mesoporous TiO2-MXene membranes

Abstract

A simple and scalable method was proposed for the preparation of the mesoporous membranes by assembling 2D MXene nanosheets and TiO2 nanoparticles (NPs) on a macroporous support. MXene nanosheets were introduced into TiO2 hydrosol, and then transformed the gel for fabrication of mesoporous TiO2@MXene membranes. Characterization results confirmed that an assembled structure of TiO2@MXene nanosheets was formed, benefiting from the nanosheets as 'floor tiles', thereby successfully inhibiting the sol infiltration into the porous support. As a result, the hydrosols could be directly coated on macroporous substrates including a disc support with an average pore size of ~100 nm and a four-channel hollow fiber with an average pore size of ~300 nm. It should be emphasized that the integrated disc or hollow fiber TiO2@MXene membranes were fabricated by only one single cycle of coating, aging and calcination. A range of advanced membrane characterization techniques were employed to study the ultrastructure of the fabricated membranes and the assumption of introducing nanosheets to prevent membrane defect and gel infiltration was validated.Filtration experiments revealed the resulted membranes, in particular the hollow fiber TiO2@MXene membranes, had a narrow pore size distribution, desirable rejection chacteristics and high permeate flux. The 2D nanosheet assisted TiO2 NPs assembly proposed in this work promises a simple, feasible and scalable approach for fabrication of high-performance mesoporous TiO2 membranes.

MXene Materials for Designing Advanced Separation Membranes

“…Likewise, dip coating of MXene materials on a four-channel ceramic α-Al 2 O 3 hollow fiber support was also demonstrated. [92] Another key parameter in NLM fabrication lies in the solution processability of MXene-based materials, which is also linked to the rheological properties of dispersions. It has been shown that the colloidal dispersions of Ti 3 C 2 T x may exhibit viscoelastic behaviors at different concentrations depending on the rate of exfoliation.…”

“…In another interesting work, researchers have prepared MXene-incorporated mesoporous TiO 2 membranes and tested them for dextran rejection (Figure 5h). [92] Importantly, they used 1.0 wt% MXene nanosheets only. They coated disc-shaped and hollow fiber α-Al 2 O 3 supports with MXene dispersion by spin coating and dip coating, respectively.…”

“…the water flux dramatically. [92] In a related work, Sun et al later varied different parameters, such as the loading ratio of MXenes, dip-coating duration, and the duration and temperature of the calcination process. [117] For 1 and 5 wt% MXene incorporations, they observed only <20% and <40% decline in water flux, respectively.…”

Ion‐Selective MXene‐Based Membranes: Current Status and Prospects

“…[171,172] For instance, Xu et al prepared MXene-based membranes via spin coating on polyacrylonitrile (PAN). [173] A dip-coating method was also reported for the preparation of MXene membranes on a ceramic α-Al 2 O 3 substrate. [173] Rheological characteristics of the MXene colloidal dispersion play a key role in synthesizing such membranes.…”

“…[112,[181][182][183][184][185][186][187][188][189][190][191][192] These appealing properties have created a lot of interest in the use of MXenes in many fields including membrane separation. [112,163,173,181,185,187,189,190,[193][194][195][196] Most of MXene-based membranes used for water purification have been benefitted from MXenes' 2D multilayers structure, especially the interlayer spacing and the nanosheets orientation. [112,173,181,187,190,196] Selfstanding and supported membranes have been fabricated from Ti 3 C 2 T x MXene.…”