Design of three dimensional porous BC2N polymorphs.

Driven by the advances of porous materials in hydrogen storage, ion filtration/separation, and catalysis, three novel 3D porous frameworks of BC 2 N compounds were designed in this study. They are characterized by a porous structure with low density formed by hexagonal arrays of carbon and boron nitride in alternating patterns. These structures contain sp 2-and sp 3-hybridized B–C, C–C, and C–N bonds. Structural stability is rigorously evaluated by means of energy, elastic constants, and phonon dispersion, confirming the thermodynamic, mechanical, and kinetic stability of the designed BC 2 N- x frameworks. First-principles calculations reveal their semiconducting nature, which is characterized by a narrow direct bandgap ranging from 0.140 eV to 0.422 eV. The mechanical properties are studied with tensile strength calculations, and results show these structures are as strong as diamond with tensile strength value of 97∼102 GPa along <010> direction. Therefore, we suggest that these BC 2 N- x structures are promising for optoelectronic device and catalysts. [ABSTRACT FROM AUTHOR]