Understanding of C/Ti‐Doped SnS₂ Photocatalytic Behaviors from Electronic Structures

The physical mechanisms governing the photocatalytic behaviors of C‐ or Ti‐doped SnS₂ are investigated based on first‐principles calculations. The calculations reveal that C atoms prefer to occupy interstitial sites around the surface, whereas Ti atoms are more likely to occupy the Sn atom positions around the surface. C atoms that occupy the C_i−2 interstitial site around the surface and inside the bulk will result in an occupied shallow defect state above the valence band maximum (VBM). The electronic lifetimes excite by visible‐light irradiation at the conduction band minimum (CBM) will be prolonged due to different real‐space positions of electrons at the CBM and the holes at the defect state. Ti atoms that occupied the Sn atom positions in the inner bulk will introduce two local shallow unoccupied defect states below the CBM, which are electron traps and delay the return of excited electrons to the valence band. The lifetime of holes at the VBM will be prolonged, The theoretical explanations based on Shockley–Read–Hall recombination theory enable the photocatalytic behavior to be understood deeply under the theoretical framework of semiconductor physics.