Chemically bonded BiVO4/Bi19Cl3S27 heterojunction with fast hole extraction dynamics for continuous CO2 photoreduction

Surface charge localization and inferior charge transfer efficiency seriously restrict the supply of reactive hydrogen and the reaction dynamics of CO₂ photoreduction performance of photocatalysts. Herein, chemically bonded BiVO₄/Bi₁₉Cl₃S₂₇ (BVO/BCS) S-scheme heterojunction with a strong internal electric field is designed. Experimental and density function theory calculation results confirm that the elaborated heterojunction accelerates the vectorial migration of photogenerated charges from BiVO₄ to Bi₁₉Cl₃S₂₇ via the interfacial chemical bonding interactions (i.e., Bi-O and Bi-S bonds) between Bi atoms of BVO and S atoms of BCS or Bi atoms of BCS and O atoms of BVO under light irradiation, breaking the interfacial barrier and surface charge localization of Bi₁₉Cl₃S₂₇, and further decreasing the energy of reactive hydrogen generation, CO₂ absorption and activation. The separation efficiency of photogenerated carriers is much more efficient than that counterpart individual in BVO/BCS S-scheme heterojunction system. As a result, BVO/BCS heterojunction exhibits a significantly improved continuous photocatalytic performance for CO₂ reduction and the 24 ​h CO yield reaches 678.27 ​μmol·g⁻¹. This work provides an atomic-level insight into charge transfer kinetics and CO₂ reduction mechanism in S-scheme heterojunction.