High photocatalytic performance of g-C3N4/WS2 heterojunction from first principles

Abstract

In this paper, the electrical and optical properties of monolayer g-C3N4, WS2 (0 0 1), and g-C3N4/WS2 heterojunction were studied in detail based on the first-principle calculations, which have been proved that the g-C3N4/WS2 heterojunction has good photocatalytic performances by realizing the separation of the photo-generated charge carriers efficiently. Moreover, according to the absorption spectrum of g-C3N4/WS2 heterojunction, we speculated that the optical properties of g-C3N4/WS2 heterojunction mainly depend on the WS2 side. The modification methods of WS2 with Mn and B co-doping and W vacancy doping were adopted to achieve overall spectral redshift. As we suspected before, the absorption spectra of g-C3N4/W8S17MnB and g-C3N4/W8S18 show significant red shift which have widen from 900 nm to near 1200 nm and over 1500 nm respectively. More excitingly, while the absorption spectrum broadened, the doped heterojunction lowered the hydrogen evolution reaction (HER) overpotential, making the catalytic reactions occur spontaneously under the potentials solely provided by the photo-generated electrons and holes in pure water. This paper provides a promising theoretical avenue for the exploration of the new and efficient visible light catalytic materials.