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

Abstract

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.