Construction Of Flower-Shaped 3D CuFe₂O₄@BiOI {110} Z-Scheme Heterojunction And Its Photoelectrocatalytic Properties

With the increasing energy crisis,it is imperative to develop new clean energy.As an important green fuel,H₂O₂is expected to replace traditional fossil fuels in the future.At the same time,a large amount of industrial wastewater and domestic sewage discharge,also caused serious environmental water pollution.Therefore,it is urgent to develop a green technology for H₂O₂ production and environmental water purification.Visible-driven photocatalysis（PEC）is a promising approach to solving energy and environmental crises.The design and construction of highly efficient and stable semiconductor photocatalyst is the core of photocatalytic technology.In this paper,a facet-dependent 3D layered microflower like CuFe₂O₄@BiOI（CFO@BiOI）Z-Scheme heterojunction bifunctional photoelectcatalyst was designed and successfully constructed,which can be used as photocathode catalyst for O₂reduction production of H₂O₂with coupled the oxidation of anode pollutants.1.BiOI-110 and BiOI-001 main materials with 3D layered flower structures that tend to grow on different exposed crystal surfaces were prepared by a simple solvothermal method with controlling the reaction time.In order to further improve the photoelectric performance of the catalyst,different qualities CFO nanoparticles were added in the process of BiOI synthesis.Heterojunction was successfully constructed by loading CFO nanoparticle on BiOI microflowers.,and the morphology,crystal structure and band structure of the materials were characterized by SEM,TEM,XRD,XPS,DRS and Mott Schottky.Transient photocurrent,EIS,PL spectrum and CV curves were used to investigate the photoelectric properties of the materials.The results showed that controlling the reaction time could realize the directional growth of BiOI different facets,compared with BiOI with{001}facet,BiOI with{110}facet had better aggregation ability of e^-and sensitivity to O₂ trapping.In addition,the layered flower structure of BiOI is conducive to light absorption and stable Z-Scheme heterojunction can be formed after loading CFO nanoparticles.On the one hand,the construction of heterojunction expands the range of light absorption of catalyst;on the other hand,the internal electric field formed when two kinds of semiconductors are in contact can further improve the efficiency of carrier separation.2.The prepared 3D layered flower-like CFO@BiOI Z-Scheme heterojunction bifunctional photocatalyst with controlled facets is used for the production of H₂O₂ and collaborative purification of pollutants in water.（1）Production of H₂O₂:the prepared semiconductor material is used as a photocathode for photoelectrocatalytic production of H₂O₂.The experimental results showed that compared with the monomer materials BiOI and CFO,the composite showed stronger photoelectrocatalytic performance,and the H₂O₂ production of CFO@BiOI-110 reached 2156μmol·L^-1 in 120 min,which was attributed to the inhibition of carrier recombination due to the construction of heterojunction.The H₂O₂yield of catalyst with different facets also have significant differences.The yield of the composite with{110}facet is 224μmol·L^-1 higher than that with{001}facet,mainly because{110}facet is more sensitive to e^-aggregation and O₂ trapping.In order to explore the influence of various factors on the H₂O₂production,the production was compared under different p H,CFO loading,gas atmosphere,catalyst dosage,and PC/EC/PEC conditions.Especially in different gas atmospheres of O₂ and air,the output of H₂O₂ is significantly different,which proves that O₂ is the key to production.Moreover,through free radical capture experiment and rotating disk linear scanning voltammetry test,·O₂^-is a necessary active species in the production of H₂O₂ reaction,which proves that H₂O₂ production mainly follows a two-step one-electron ORR reaction process.The stability of catalyst was proved by stability test and cycle test.The Z-Scheme charge transfer mode of heterojunction was further demonstrated by XPS before and after the reaction irradiation.（2）Production of H₂O₂ collaborates with pollutant oxidation:Malachite green（MG）,Enrofloxacin（ENR）,and As（III）pollutants were used as model pollutants to evaluate the coupling enhancement performance of H₂O₂ production by anodic oxidation of CFO@BiOI in polluted water bodies.The experimental results show that the dual-function coupled photoelectrocatalytic system has good catalytic performance for all kinds of pollutants,and the production of H₂O₂ can be increased while the pollutants are oxidized and degraded,and the effect of synchronous redox can be achieved by synergistic promotion.In conclusion,CFO@BiOI dual-function photoelectrocatalyst not only has good catalytic activity for H₂O₂ production by ORR,but also achieves coupled oxidative degradation of various pollutants in water.The design provides a new strategy for H₂O₂ production and water pollution treatment.