Preparation And Properties Of Iron-Doped Mesoporous Titanium Dioxide

Objective:The preparation of TiO₂with visible light catalytic ability is key to wide its application for bactericidal antivirus.The preliminary experimental study showed that the visible light utilization of mesoporous hydrogen titanate H₂Ti₃O₇ and mesoporous anatase TiO₂ obtained from the reaction system of ethylenediamine?EDA?and titanium tetrachloride was too low.In this study,the study to improve the utilization of visible light by doping iron with mesoporous hydrogen titanate H₂Ti₃O₇ and mesoporous anatase TiO₂was presented.The effects of iron doping amount and hydrothermal time on their morphology,light absorption,methylene blue adsorption and photocatalytic activity were also studied.Methods:The EDA was added into a solution contaiing Fe³⁺to form a Fe³⁺coordination compound,then titanium tetrachloride was added dropwise into the solution to produce TiCl₄-EDA intermediate.The products of iron-doped mesoporous hydrogen titanate and anatase TiO₂ were obtained by mixing the intermediate with distilled water and then hydrothermally reacted at 120?or 150?.The products were characterized by static nitrogen adsorption,X-ray diffraction?XRD?,transmission electron microscopy?TEM?,UV-Vis absorption and X-ray photoelectron spectroscopy?XPS?.The photocatalytic activity and adsorption properties of the products were studied using methylene blue?MB?as the target.Results:The iron-doped hydrogen titanate was in shape of the mesoporous.The XRD and TEM showed that its mesoporoe was in the shape of short rod-shaped.The doping of iron decreased the grain size of product.The specific surface area and pore structure analysis showed that the hydrothermal time of 12 h presents a higher specific surface area?433.5 m²/g?and mesopore volume?0.42 cm³/g?with an average pore size in the range of3.7-5.5 nm.FT-IR and XPS results showed that iron has been incorporated into the product and iron exists in the form of Fe³⁺.The UV-Vis results showed that the absorption threshold of iron-doped products was obviously red-shifted,and the light response range was broadened.The product of methylene blue adsorption agrees well with quasi-two adsorption kinetics model.The results of visible light catalysis showed that the photocatalytic degradation to methylene blue for product doped iron of 0.69%presents the highest photocatalytic degradation.It reaches to 1.5 times of undoped iron sample and 1.3times of P25.After 4 cycles of photocatalytic degradation,the degradation rate was still about 80%.The iron-doped mesoporous anatase TiO₂ was preparad.XRD and TEM results showed that the products were rod-shaped anatase TiO₂.The prolonged hydrothermal time lead to higher crystallinity and larger crystallite size.Iron-doping has no significant effect on the XRD diffraction peaks and crystallite size of the product.After calcining,the crystallinity became better,the grain size became larger,and the crystal form was still anatase at 600?;The specific surface area and pore structure analysis showed that the hydrothermal time of 6 h presents a large specific surface area?355.5 m²/g?,and the hydrothermal time of 12 h presents a large mesoporous volume?0.77 cm³/g?.The average pore size mainly distributed between 3⁵ nm and 16⁶4 nm.With the extension of the hydrothermal time,the micropores transformed to the mesopores,the mesopores transformed to the macropores.Iron-doping and calcining reduced the texture parameters,such as specific surface area and pore volume of the product.The UV-Vis results showed that the absorption threshold of iron-doped products was obviously red-shifted.The results of visible light catalysis showed that the photocatalytic degradation to methylene blue for product doped iron of 0.69%presents the highest photocatalytic degradation.Conclusion:The addition of iron in mesoporous hydrogen titanate H₂Ti₃O₇ and mesoporous anatase TiO₂ can significantly improve their photocatalytic activity to methylene blue,although the addition of iron reduce the texture parameters,such as specific surface area and pore volume.The structure of the iron-doped product has a decisive effect on the adsorption.Iron-doping has no effect on the crystal form of the both.mesoporous hydrogen titanate H₂Ti₃O₇ and mesoporous anatase TiO₂.The calcination temperature of 300⁶00?does not change the crystal form of anatase TiO₂.