Rational Design of MXene Hollow Fiber Membranes for Gas Separations.

Zhang, Yiming; Sheng, Kai; Wang, Zheng; Wu, Wenjia; Yin, Ben Hang; Zhu, Junyong; Zhang, Yatao · Nano Lett · 2023

basic_science · Level V

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Abstract

One scalable and facile dip-coating approach was utilized to construct a thin CO<sub>2</sub>-selection layer of Pebax/PEGDA-MXene on a hollow fiber PVDF substrate. An interlayer spacing of 3.59 Å was rationally designed and precisely controlled for the MXene stacks in the coated layer, allowing efficient separation of the CO<sub>2</sub> (3.3 Å) from N<sub>2</sub> (3.6 Å) and CH<sub>4</sub> (3.8 Å). In addition, CO<sub>2</sub>-philic nanodomains in the separation layer were constructed by grafting PEGDA into MXene interlayers, which enhanced the CO<sub>2</sub> affinity through the MXene interlayers, while non-CO<sub>2</sub>-philic nanodomains could promote CO<sub>2</sub> transport due to the low resistance. The membrane could exhibit optimal separation performance with a CO<sub>2</sub> permeance of 765.5 GPU, a CO<sub>2</sub>/N<sub>2</sub> selectivity of 54.5, and a CO<sub>2</sub>/CH<sub>4</sub> selectivity of 66.2, overcoming the 2008 Robeson upper bounds limitation. Overall, this facile approach endows a precise controlled molecular sieving MXene membrane for superior CO<sub>2</sub> separation, which could be applied for interlayer spacing control of other 2D materials during membrane construction.