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Based on the fact that the photo-Fenton process can directly use solar energy to degrade various pollutants, it has received widespread attention. However, it has attracted widespread attention due to the rapid recombination of photo-generated carriers and the low light response range. Therefore, the construction of a Z-scheme heterojunction in this paper can effectively enhance the electron–hole separation, increase the reduction and oxidation potential, and enhance the redox capability of the photocatalysis. This paper reports the successful preparation of visible-light-induced ZnFe2O4/BiOI composite photocatalysis. There is a Z-scheme heterojunction structure of ZnFe2O4 and BiOI. At the same time, the PL and UV absorption spectra showed that the light absorption performance of the composite nanomaterials was enhanced, the photo-generated carrier recombination rate was reduced, and the photo-Fenton performance was also significantly improved. And the photocurrent of ZnFe2O4/BiOI is more than 27 times that of pure ZnFe2O4. In addition, ZnFe2O4/BiOI can degrade the simulated pollutant RhB 100% within 20 min under simulated sunlight. It shows that ZnFe2O4/BiOI binary composite has excellent photo-Fenton properties. In addition, ZnFe2O4/BiOI still maintains a high photo-Fenton ability after three cycles. Therefore, it has potential application prospects of the industrial photodegradation of organic pollutants. [ABSTRACT FROM AUTHOR]

• BiOI is an excellent connector between ZnFe 2 O 4 and AgI to form a double Z-type heterojunction structure ZnFe 2 O 4 /BiOI/AgI composite through precise electronic regulation. • The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. • Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. As a bridge, BiOI nanosheets connect ZnFe 2 O 4 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 ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI, the photo-Fenton degradation RhB of ZnFe 2 O 4 /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 ZnFe 2 O 4 /BiOI/AgI is lower than that of ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI because of reducing the recombination rate of photogenerated carriers. ZnFe 2 O 4 /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. [Display omitted] [ABSTRACT FROM AUTHOR]

The binary flower-like BiOI/CoFe 2 O 4 photocatalysts with magnetic retrievability were successfully synthesized via coprecipitation method. The effects of composite ratio on the microstructure, morphology, optical, photo-electrochemical and photocatalytic properties of the samples were studied. The experimental results show that BiOI/CoFe 2 O 4 nanocomposites contain tetragonal structure BiOI and cubic spinel structure CoFe 2 O 4 with good crystallization. Spherical CoFe 2 O 4 nanoparticles are uniformly decorated on the surface of BiOI nanosheets to establish hierarchical flower-like 3D- BiOI/CoF 2 O 4 heterojunctions. BiOI/CoFe 2 O 4 nanocomposites show excellent visible light absorption ability. PL spectra show the intensity decrease for BiOI/CoFe 2 O 4 nanocomposites. BiOI/CoFe 2 O 4 nanocomposites can promote the separation of photon-generated carriers, improve the migration efficiency, and improve the redox activity of nanocomposites. BiOI/CoFe 2 O 4 nanocomposites exhibit better photocatalytic activity during the process of degrading the RhB dye solution under the irradiation of simulated visible light. The degradation efficiency of BiOI/CFO-3 photocatalysts is 80.24% after 3 cycles, and exhibit better recyclable stability. Also, ·O 2 − is the main reactive species in the degradation process, which plays a crucial role in the RhB degradation. Image 1 • The binary flower-like BiOI/CoFe 2 O 4 photocatalysts with magnetic retrievability were synthesized via coprecipitation method. • BiOI/CoFe 2 O 4 nanocomposites show excellent visible light absorption ability. • BiOI/CoFe 2 O 4 nanocomposites accelerate the separation and migration efficiency of carriers, and improve the redox activity. • BiOI/CFO -3 samples have the best photocatalytic performance, and the degradation efficiency is 80.24% after 3 cycles. [ABSTRACT FROM AUTHOR]