First-principles study of nitrogen defect g-C3N4/WS2 heterojunction on photocatalytic activity

In this work, first-principles density functional theory simulations have been performed to investigate the influence of nitrogen (N) defect on the supercell structure, electronic structure and photocatalytic properties of g-C3N4/WS2 heterojunctions. Analyses of calculated binding energies and the lattice mismatch ratios led us to confirm that N-deficient g-C3N4 and WS2 were in parallel contact and form a stable heterojunction. Furthermore, the work functions, molecular dynamics simulations, charge density differences, band structures, DOS, electronic and optical properties and absorption spectra of different g-C3N4/WS2 heterojunctions have been analyzed in detail. It is revealed that the compositing of N-deficient g-C3N4 with WS2 improves the separation of photoinduced electron-hole pairs. N-defect enhances the visible light absorption of the heterojunction, due to the introduction of impurity energy levels. Moreover, the introduction of defect species further improves the photocatalytic performance of g-C3N4/WS2 heterojunction in the visible region.