▎ 摘　　要

2D porous graphene-like sheets with specific CN stoichiometric ratio (h-C2N and h-C5N2) were theoretically investigated based on DFT method. The calculated results show h-C2N and h-C5N2 are both semiconductors with direct band gap 1.72 and 1.10 eV. The CBM positon for h-C2N is high, but the potential positions for h-C5N2 are very low. h-C2N is predicted as good photo- or electro-catalyst to produce hydrogen or CO2 reduction but h-C5N2 is not. Defects construction and tailoring 2D h-C2N and h-C5N2 sheets to 1D nanoribbons were used to tune the band structures. The defective derivatives are n-type semiconductor with two doping levels contributed by O atoms. The doping levels could capture electrons as trap levels and O atoms could coordinate metal to obtain single-atom catalyst. 1D nanoribbons show bigger band gaps and higher CBM potential position than corresponding 2D sheets, which is thought to show better properties on photo- or electro-catalysis.