Unusual Mechanism Behind Enhanced Photocatalytic Activity and Surface Passivation of SiC(0001) via Forming Heterostructure with a MoS2 Monolayer

A two-dimensional (2D)/three-dimensional (3D) hybrid heterostructure has recently emerged as an effective method for improving photocatalytic efficiency. In this work, we perform a comprehensive first-principles study of the structural, electronic, and optical properties of a novel 3D-SiC/2D-MoS2 heterostructure. The calculation results reveal that the SiC(0001) surface/MoS2 monolayer integrated heterostructure in Schottky contact with a new chemical bonding contributed to the surface adhesion and optoelectronic properties. Meanwhile, the valence and conduction band-edge positions of SiC and MoS2 changed with the Fermi level and formed a desired type-II band alignment, which greatly facilitate the rapid separation of photogenerated carriers. Moreover, the surface state of SiC(0001) can be removed when combined with MoS2 , and their band gap is also reduced. Furthermore, Bader charge and charge density difference indicated that there is a remarkable separated distribution of electrons and holes at the interface. These results demonstrated that the band structure of the 3D-SiC/2D-MoS2 heterostructure had significant advantages to improve the photocatalytic efficiency under visible-light irradiation.