Atomic interfacial structure and charge transfer mechanism on in-situ formed BiOI/Bi2O2SO4 p–n heterojunctions with highly promoted photocatalysis

Developing novel and highly efficient Bi-based photocatalysts induced by visible light, and determining their interfacial mechanism represent two significant challenges in the environmental catalysis field. Herein, the preparation of bismuth oxysulfate, Bi2O2SO4, and in-situ couping with BiOI to form a novel BiOI/Bi2O2SO4 p–n heterojunction are described. The optimized BiOI/Bi2O2SO4 heterojunction exhibits remarkable photocatalytic NO oxidation under visible-light irradiation, with multifold higher activities than pristine BiOI or Bi2O2SO4. The BiOI/Bi2O2SO4 heterojunction enforces a directional charge transfer induced by the internal electric field, and substantially boosts the charge separation of photogenerated electron-hole pairs at the Bi2O2SO4 and BiOI interface. The electron-rich interfacial environment promotes reactant activation and reactive oxygen species generation, and prevents the formation of toxic NO-derived by-products, resulting in superior photocatalytic activity. Considered in its entirety, the current work introduces a promising Bi-based photocatalyst and provides guidance for the rational design of highly efficient heterojunction photocatalysts.