An oxygen-vacancy rich ZnFe2O4/BiOI/AgI heterojunction for enhanced photocatalytic and photo-Fenton performance via double Z-scheme structure

Abstract

As a bridge, BiOI nanosheets connect ZnFe2O4 nanoparticles and AgI clusters (∼300 nm) via hydrothermal-coprecipitation. A ternary composite with a double Z-type heterojunction structure is obtained through precise electronic regulation. Compared with ZnFe2O4 and ZnFe2O4/BiOI, the photo-Fenton degradation RhB of ZnFe2O4/BiOI-AgI-3 samples is obviously improved under simulated sunlight. Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. The main active specie in photo-Fenton degradation is ·OH. The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. Notably, the intensity of PL luminescence ZnFe2O4/BiOI/AgI is lower than that of ZnFe2O4 and ZnFe2O4/BiOI because of reducing the recombination rate of photogenerated carriers. ZnFe2O4/BiOI/AgI composites have excellent stability of photo-Fenton degradation. Furthermore, the formation of a built-in electric field inhibits the recombination of electron-hole pairs, enhances visible light absorption, results in improving the efficiency of ternary composite materials to degrade pollutants.