Theoretical study of the photocatalytic activity of hBNC/MoSX (X = Se, Te) heterojunctions

Abstract

The effects of the introduction of C-C bonds on the stability, electronic structure, work function, and optical properties of hBN/MoSX heterojunctions are investigated based on the density functional theory plane wave ultra soft pseudopotential method. The results show that the hBNC/MoSX heterojunctions have low binding energies (−4.066 eV to −4.777 eV) and lattice mismatch ratios (2.62 % and 1.44 %) and can be stabilized at room temperature of 300 K, indicating that they possess excellent stability. By comparing the electronic structure with that of the hBN/MoSX heterojunction, it is found that the introduction of C-C bonds can effectively adjust the band gap of the heterojunction. The bandgap of hBN/MoSX varies from 1.018 eV to 1.168 eV with small variations. The hBNC/SMoSe and hBNC/SMoTe heterojunctions have bandgaps of 0.309 eV and 0.494 eV, with significantly reduced bandgaps and orbital hybridization. The number of electrons in the excited state increases, which makes the electron leap easier and is beneficial to improve the response of the heterojunction to visible light. Due to the presence of the built-in electric field at the interface, the compounding of photogenerated electron-hole pairs can be effectively suppressed, which greatly enhances both the heterojunction photocatalytic ability and carrier migration. Compared with the hBNC monolayer system, both were red-shifted in the low-energy region. hBNC/SMoTe and hBNC/SMoSe showed the best absorption of light in the low-energy region, indicating excellent photocatalytic performance.