Flower-like hierarchical architecture of BiOI/ZnO p-n junction composites with high-efficient visible-light photodegradation activities

Abstract

Photodegradation has been taken as a promising technology in solving global environmental pollution. In this paper, the flower-like hierarchical architecture of BiOI/ZnO p-n junction composites were synthesized by coating BiOI nanosheets on the flower-like hierarchical architecture of ZnO prepared by a simple hydrothermal method. The as-synthesized BiOI/ZnO composites were characterized by various techniques. The photocatalytic activities of the BiOI/ZnO composites were examined by degrading the Methylene Blue under visible-light conditions. The results show that the formation of the p-n junction between n-type ZnO and p-type BiOI has broadened the light absorption range, modified the band gap and specific surface area, facilitated the separation and transfer of photogenerated carriers of BiOI/ZnO composites. The visible-light photodegradation rate for 15 wt% BiOI/ZnO composites reached to 94% in 3 h with excellent reusability. The photodegradation obeys first-order reaction kinetic with rate constant of 15.64 × 10−3 min−1 for 15 wt% BiOI/ZnO, which is 4.4 and 24.3 times of that of ZnO and BiOI, respectively. The photodegradation mechanism was proposed based on the analyses of the energy band gap in the formation of the p-n junction.