Preparation And Photocatalytic Ability Of MoO₃/Fe₂O₃ Micro-nanomaterials

As an n-type semiconductor,molybdenum trioxide?MoO₃?has a band-gap energy between 2.8 and 3.2eV and is non-toxic and low cost.Therefore,MoO₃ has been widely used in photocatalysis applications.However,MoO₃ suffers from many drawbacks,such as small particle size,difficulty of recycling,and secondary pollution.When MoO₃ particles are loaded onto the magnetic nanoparticles,the catalyst can be recovered using an external magnetic field.Herein,?-Fe₂O₃ is used as the magnetic core,we successfully synthesized the ?-Fe₂O₃@MoO₃ and ?-Fe₂O₃@SiO₂/MoO₃ composite nanomaterials.We investigated the photocatalytic performance and magnetic ability of the materials with methylene blue?MB?as the target degradation material.The composition,morphology and properties of samples were studied using various techniques,including X-ray powder diffraction?XRD?,Field emission scanning electron microscopy?FE-SEM?,Transmission electron microscope?TEM?,Fourier transform infrared spectroscopy?FT-IR?,X-ray photoelectron spectroscopy?XPS?,UV Vis diffuse reflectance spectroscopy?UV-vis-DRS?and vibrating sample magnetometry?VSM?.The results are as follows:?1?we synthesized magnetic ?-Fe₂O₃@MoO₃ core-shell composites via a hydrothermal method and controlled the calcination process.During the construction process,a hydrophilic carbonaceous layer acted as the linker between Fe₃O₄ and [Mo?NH₃?₆]⁶⁺.The effects of calcination temperature on the magnetic and photocatalytic properties and the intermediate impurity phases of the materials were studied using various techniques.The results show that all catalysts calcined at different temperatures had good photocatalytic ablity.Moreover,the ?-Fe₂O₃@MoO₃ core-shell photocatalyst that was obtained after calcining at 400 °C has good magnetic responses and cyclic stability.The Fe₂?MoO₄?₃ impurity phase was formed with the increase in the calcination temperature,and the magnetic ability and photocatalytic activity were reduced.The photocatalytic activity is enhanced,primarily due to the influence of the impurity levels,and the energy difference of the semiconductor between MoO₃ and ?-Fe₂O₃ can effectively promote the separation of photo-induced electron-hole pairs.?2?The SiO₂ interlayer was introduced into the ?-Fe₂O₃@MoO₃ core-shell structure photocatalyst by modified St?ber method.Then,?-Fe₂O₃@SiO₂@MoO₃ magnetic photocatalyst was prepared.The effects of SiO₂ interlayer on the magnetic properties and photocatalytic properties of the materials were investigated by magnetic texting and photocatalytic experiments.?3?The Fe₃O₄ micro-nanoparticles were synthesized by solvothermal method,and then SiO₂ was coated on the surface of Fe₃O₄ to form Fe₃O₄@SiO₂ core-shell materials by modified St?ber method.Subsequently,using ammonium molybdate as precursor,the ?-Fe₂O₃@SiO₂/MoO₃ magnetic photocatalysts were obtained by evaporation solvent and calcinations process.The effects of morphology of MoO₃ in the sample on photocatalytic properties of materials were investigated by a series of characterization.The results show that the increase of MoO₃ content leads to the morphology of MoO₃ was chanced.At the same time,with the increase of MoO₃ content,the specific surface area and the photocatalytic activity of the photocatalyst increased.