Electronic properties of g-C3N4/CdS heterojunction from the first-principles

In this work, electronic structures of two-dimensional (2D) g-C3N4/CdS heterojunction are systematically investigated by means of the first-principles calculations. Our results indicate that g-C3N4 monolayer and CdS monolayer form a standard type-Ⅱ heterojunction, with both the valence band maximum (VBM) and the conduction band minimum (CBM) of CdS monolayer higher than those of g-C3N4 monolayer, and the water reduction and oxidation potentials lie in-between the VBM and CBM of g-C3N4/CdS heterojunction. Moreover, the charge density difference of g-C3N4/CdS heterojunction indicates that an internal electric field forms between g-C3N4 monolayer and CdS monolayer, which will further restrain the recombination of photogenerated carriers. These results suggest that g-C3N4/CdS heterojunction is beneficial to enhance the efficiency of photocatalytic water splitting under visible-light irradiation.