Preparation And Properties Of Fe-based Metal Oxide Photocatalysts From Coordination Polymer Templates

Photocatalytic technology can realize the effective conversion from solar energy to chemical energy.It can be applied for the treatment of organic pollutants,and it can decompose organic pollutants in water into non-toxic inorganic products.The preparation of visible light-responsive semiconductor photocatalysts with a suitable bandgap and the promotion of effective separation of photogenerated electron-hole pairs are the key to the practical application of photocatalytic technology.Iron-based oxides have suitable bandgaps and chemical stability.The structure has an important influence on the photocatalytic performance of iron-based oxides and composite oxides,and a hollow structure or a hierarchical structure is beneficial to visible light absorption and carrier separation.The unique structure and porosity of metal organic coordination polymers help to develop a series of nanomaterials with specific controllable morphology.Transformed from a metal organic coordination polymer with a particular morphology,an iron-based oxide or an iron-based composite oxide with the desired morphology can be obtained.A magnetically ZnFe₂O₄/g-C₃N₄ composite photocatalyst is prepared by a simple solvothermal method combined with subsequent heat treatment.Precursor microspheres are composed of nanoparticles,whose diameter is limited due to the space-constrained effect of g-C₃N₄ nanosheets.After the pyrolysis the secondary structure is well preserved.The structure of ZnFe₂O₄/g-C₃N₄ heterojunction greatly improves the photodegradation efficiency of methylene blue and Rhodamine B under visible light.In addition,the composite photocatalyst is chemically resistant to photo-corrosion and its ferromagnetic properties make it magnetically recyclable and reusable.Fe-MIL materials are prepared by microwave solvothermal method.A hollow rod-like morphology precursor with a hierarchical structure is obtained.Different heat treatment temperature conditions bring about different phases of iron oxide materials.It is found that theγ-phase andα-phase composite Fe₂O₃ photocatalyst obtained from the500℃ pyrolysis of the precursor has better performance because the two species with the matching energy band structure are tightly combined to construct an effective phase junction.Photogenerated electrons and holes are effectively separated.Iron oxide can be used as a lithium negative electrode material.With Fe-MIL material prepared by the microwave solvothermal method as a precursor,γ-Fe₂O₃ material is obtained.When used as a negative electrode material,the obtainedγ-Fe₂O₃ material exhibits excellent specific capacity and good cycle stability.