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 CX and CX (X = O, S and Se) are found to have great thermodynamic and dynamic stabilities, and CX 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 CS (4.14 eV energy gap). Moreover, the intrinsic pore sizes of CSe are suitable to sieve He from the He/CH 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.