Engineering BiVO₄@Bi₂S₃ heterojunction by cosharing bismuth atoms toward boosted photocatalytic Cr(VI) reduction

The photocatalytic efficiency is limited by poor charge separation efficiency and high carrier transport activation energy (CTAE) of photogenerated electron/hole pairs than traditional semiconductor. Hybridizing nanostructure with two staggered alignment band structure is proved as an effective strategy to mitigate these two challenges but still suffers a strong coulomb electrostatic repulsive force between two heterogeneous semiconductors. Here, we steer a friendly sulfurization process to construct BiVO₄@Bi₂S₃ heterojunction with a scenario of cosharing Bi atoms. The intimate atomic-level contact between BiVO₄ and Bi₂S₃ not only enhances the visible-light absorption and lowers CTAE, but also accelerate carrier's separation efficiency, which enables it to deliver the best photocatalytic performance toward reduction of Cr(VI). BiVO₄@Bi₂S₃ only needs less than 40 min to completely reduce 50 ppm Cr(VI) solution. The type II heterojunction photocatalytic mechanism is systematically studied to decipher the carriers' transfer track between BiVO₄ and Bi₂S₃. Our new finding of engineering inorganic heterojunction by cosharing atoms opens a new avenue to other similar materials for potential applications.