The tesseract in two dimensional materials, a DFT approach

A series of novel two-dimensional materials inspired from a 4D polytope, tesseract, have been proposed by density functional theory (DFT) based computations. Both C₂₄X₁₂ and C₁₆X₁₆ (X = O, S and Se) are found to have great thermodynamic and dynamic stabilities, and C₂₄X₁₂ exhibited excellent thermal stability up to 1000 K. All these 2D crystals are semiconductors with 2.17 eV to 3.35 eV band gaps at the HSE06 theoretical level, except for C₂₄S₁₂ (4.14 eV energy gap). Moreover, the intrinsic pore sizes of C₂₄Se₁₂ are suitable to sieve He from the He/CH₄ mixture, with over 80% separation ratio and nearly 100% selectivity. Our findings not only enlarged the boundary of the 2D family, but also offered another potential method to recover helium from natural gas at ambient conditions.