Preparation And Photocatalytic Performances Of Several Ferrite?ZnFe₂O₄,LaFeO₃? Semiconductor Heterostructures Photocatalysts

Traditional photocatalyst TiO₂ nanomaterials can only absorb a very low proportion of ultraviolet light in the solar spectrum due to its wide band gap,and the quantum efficiency is relatively low.Because spinel ferrites have a narrow band gap?about 2 eV?and strong corrosion resistance,which is considered as a promising photocatalyst.Therefore,developing the novel photocatalyst with visible light activity is an important subject for further study.In this paper,based on the research status of photocatalytic degradation of organic pollutants and the influence of catalytic activity on the basis of ZnFe₂O₄ and LaFeO₃,this paper summarizes the design and fabrication of ZnFe₂O₄ and LaFeO₃heterostructures for high efficient photodegradation of organic dyes,in which the research contents and achievements are as following two aspects.1)In this study,a new magnetically separable Cu₂ZnSnS₄/ZnFe₂O₄ p-n heterostructured nano-photocatalyst was first prepared by a facile two-step hydrothermal method.The characterizations of morphology and microstructure revealed that the p-type Cu₂ZnSnS₄?CZTS? nanosheets were successfully assembled on the surface of ZnFe₂O₄?ZFO? nanospheres,forming a CZTS/ZFO p-n heterostructures.A series of test results showed that this p-n heterostructures could not only efficiently expand spectral response and promote photoinduced charges separation,but also increase the specific surface areas for photocatalytic and photo-Fenton reactions.All these factors resulted in the p-n heterostructured CZTS/ZFO nano-photocatalyst plus H₂O₂ having a significantly enhanced photocatalytic activity for degradation of methyl orange?MO?at visible light irradiation,compared to the pure ZFO,the removal efficiency available reached up to 91%within 120min.These outstanding performances should be ascribed to the synergistic enhancement effects of the CZTS/ZFO p-n heterostructure combining with photo-Fenton mechanism,which could be confirmed by exploring the dominant effects of radical scavengers and the yield of hydroxyl radicals?·OH? on the surface of the p-n heterostructured nano-photocatalyst with and without contribution of photo-Fenton reaction for the MO removal.Furthermore,the CZTS/ZFO p-n heterostructured nano-photocatalyst exhibited remarkably stable and easy separated performances,suggesting a promising application for the photo-oxidative degradation of organic contaminants.2)A new heterostructures of NiS/LaFeO₃?NiS/LFO?,which has the morphology of LFO nanoparticles fixed NiS nanosheetes,has been well designed and successfully fabricated by a facile two-step hydrothermal method.To be used in photodegradation of anion MO dye,it can possess the removal efficiency of 90.9%and reaction rate constant of 0.0169 min^-1,being approximately 12 times higher than that of pure LFO(0.0014 min^-1).Detailed investigations show that such excellent photocatalytic performance of NiS/LFO should be attributed to its larger specific surface areas to provide more active sites,nanosheet structure of NiS to unimpededly transport the photogenerated electrons,and the matched energy band of NiS and LFO for better interfacial electrons separation and transfer.The present study might induce a new means to design and fabricate new LFO-based heterostructured photocatalysts for high efficient photodegradation.