Unveiling the potential of MXenes for H₂ purification and CO₂ capture as an emerging family of nanomaterials

Abstract

MXenes have gained deep interest in various applications since the discovery of their first member, Ti 3 C 2 T x , in 2011 due to their exceptional properties. They are accepted as promising candidates for gas separation applications. Here, we aimed to identify CO 2 /H 2 adsorption-based separation performances of blooming MXene family including 730 members under various process conditions via molecular simulations.We reported that 62% and 83% of MXenes revealed percent regenerability (R%) >90% for single gas adsorption under pressure and vacuum swing adsorption conditions, respectively while these percentages reached 98% and 95% with the increase in interlayer distance. Ti 0.4 Nb 1.6 C, V 2 Ti 2 C 3 , Ti 2 VC 2 , and Ti 1.2 Nb 0.8 C are best MXenes in single gas adsorption whereas for CO 2 /H 2 :25/75 mixture, top MXenes dominantly consist of Cr, Mo, and W. We reported an online MXene database (https://mem-ces. com/mxenes/) which covers simulated adsorbent metrics of MXenes for CO 2 /H 2 separations. Examining this MXene database would be beneficial to conceptually understand MXene design for CO 2 /H 2 separation.

Can MXene be the Effective Nanomaterial Family for the Membrane and Adsorption Technologies to Reach a Sustainable Green World?

“…While studies on the effect of interlayer spacing on gas separation of MXene membranes continue, on the other hand, new approaches have been sought to enhance selectivity without sacrificing from permeability. Considering the adsorption process, in our recent atomistic scale simulation study, , we have targeted to quantitatively identify the alteration of the CO 2 working capacity and CO 2 /H 2 adsorption selectivity of 730 MXene adsorbents after the enhancement in the interlayer distance. Therefore, adsorption simulation of the proposed MXene database was carried out for structures having two different interlayer distances (3.5 and 6.5 Å).…”

“…Therefore, researchers who aim to benefit from MXene nanomaterials in these two emerging separation technologies can find a foothold and determine where to begin in this booming investigation field. To unveil the potential of each MXene member for each separation application that was covered in this review, we believe future efforts should be dedicated to the following: (i) Almost thousands of distinct compositions have been accumulated, including surface terminations, multielement, multilayered MXenes, etc . However, many more layered ternary metal carbides and nitrides or more complex ones are waiting to be transformed to MXene using either MAX or non-MAX phase etching methods.…”

“…Considering the adsorption process, in our recent atomistic scale simulation study, 157,158 we have targeted to quantitatively identify the alteration of the CO 2 working capacity and CO 2 / H 2 adsorption selectivity of 730 MXene adsorbents after the enhancement in the interlayer distance. Therefore, adsorption simulation of the proposed MXene database was carried out for structures having two different interlayer distances (3.5 and 6.5 Å).…”

“…We recorded a considerable decrease in both CO 2 /H 2 adsorption selectivity and CO 2 working capacity of 76% of the total MXene structures in numbers. 157,158 As a result of electrostatic and vdW interactions, CO 2 can be easily kept within the MXene nanochannels at the short interlayer distance, and the effective gas adsorption can be observed for MXene adsorbents. One of the approaches that was intensely focused is the intercalation of MXene nanochannels via several types of molecules.…”

Tubular MXene/SS membranes for highly efficient H2/CO2 separation

“…Although the polymeric membranes are easy to prepare at low cost, their separation performance is usually limited by the Robeson upper bound, where the gas permeability and selectivity have a trade-off phenomenon, thus the corresponding H 2 /CO 2 separation performance is far away from the requirement for industrialization. [8][9][10][11][12][13] Many other membranes composed of metal organic membranes (MOFs), covalent organic frameworks (COFs), zeolite molecular sieves (Zeolites), or other types of materials are also restricted from complex and time-consuming preparation process, difficulty in forming a continuous defect-free membrane layer, high cost, and so on. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] In this decade, a kind of lamellar membrane based on 2D materials has attracted increasing attention, which shows the potential to break through the performance upper bound of traditional membranes.…”