▎ 摘　　要

Using first-principles calculations, we investigate the structural and electronic properties of monolayer porous graphene (C), BN, and BC2N sheets. All the porous C, BN, and BC2N sheets with one-hydrogen passivation exhibit direct-band-gap semiconducting behaviors. The porous BN sheet has a larger band gap than the porous C one, whereas the porous BC2N sheets have variable band gaps depending on the atomic arrangements of B, C, and N atoms. The stablest conformation of porous BC2N sheets is composed of C and BN hexagons, whereas with two-hydrogen passivation, it becomes the structure containing continuous BN and interrupted C zigzag lines. Furthermore, due to the sp(3) hybridization of the edge atoms, the two-hydrogen passivation induces the changes of band gaps as well as direct-to-indirect band-gap transitions in all the porous sheets. We also find that it is more Possible to form the porous C and BC2N structures in experiments than the porous BN ones. Our studies demonstrate that the porous C, BN, and BC2N sheets band engineering by different hydrogen passivations.