Graphdiyne Pores: “Ad Hoc” Openings for Helium Separation Applications

Abstract

Two-dimensional (2D) materials deriving from graphene, such as graphdiyne and 2D polyphenylene honeycomb (2DPPH), have been recently synthesized and exhibit uniformly distributed sub-nanometer pores, a feature that can be exploited for gas filtration applications. Accurate first principles electronic structure calculations are reported showing that graphdiyne pores permit an almost unimpeded helium transport while it is much more difficult through the 2DPPH openings. Quantum dynamical simulations on reliable new force fields are performed in order to assess the graphdiyne capability for helium chemical and isotopic separation. Exceptionally high He/CH 4 selectivities are found in a wide range of temperatures which largely exceed the performance of the best membranes used to date for helium extraction from natural gas.Moreover, due to slight differences in the tunneling probabilities of 3 He and 4 He, we also find promising results for the separation of the fermionic isotope at low temperature.

Efficient helium separation of graphitic carbon nitride membrane

“…These porous membranes can act as natural molecular sieves, and have great potential for future industrial applications, such as hydrogen [33][34][35][36][37][38][39][40], isotope [41][42][43][44], and other gas separation and purification [45]. Among these porous structures, g-C 3 N 4 has attracted considerable attention owing to its potential applications in solar energy conversion [46][47][48], spintronics devices [49,50], energy storage [51] etc.…”

“…Most of the membranes, such as the porous silicene [17,18], polyphenylene [33,34,43] or graphdiyne [36,37,44], fail to separate He from H 2 , as the energy barriers of H 2 and He passing through these membranes are almost equal, as shown in Table 2. It is interesting to see that for the g-C 3 N 4 membrane, the energy barrier of…”

“…Here, we assumed a classical Boltzmann distribution for the velocities of both 3 He and 4 He as suggested by previous studies [19,20,22,43,44]. This strategy not only provides a more conservative estimation of 3 He/ 4 He selectivity, but also avoids the complexity of dealing with a mixed nonideal quantum gas composed of fermionic 3 Although the g-C 3 N 4 membrane exhibits great selectivity of 3 He at low temperature, the transmission probability is 10 -34 at 49 K (Fig.…”

First principles investigation of hydrogen physical adsorption on graphynes' layers

“…The number n of acetylenic linkages which connect the benzene rings defines the different graphyne-n species and the first three members of the family are known as graphyne, graphdiyne and graphtriyne, respectively [7], and they feature nanopores of increasing size. The successful synthesis of graphynes has led to important theoretical studies devoted to their application as effective single-layer membranes for gas separation and water filtration technologies [8][9][10][11].…”

“…More accurate estimations for the noncovalent H 2 -graphynes interaction are therefore desirable and their calculations would require reliable computational approaches. Our choice is to use the "coupled" supermolecular second-order Møller-Plesset 4 perturbation theory (MP2C) which has been reported to provide reliable estimations for weakly bound systems such as rare gas-fullerene [19] and -coronene [20] as well as water(rare gas)-graphynes' pores [10,11].…”