Preparation And Application Of Nano-SrTiO₃ And Its Derivatives

Strontium titanate（SrTiO₃）is an inorganic compound with a typical perovskite structure and belongs to the cubic system.Due to SrTiO₃ has the advantages of high dielectric constant,low dielectric loss,and good thermal stability,which makes it widely used in ceramics,electronics,machinery and other industries.SrTiO₃ is used for microwave oven capacitors,substrates for epitaxial growth of superconductors,different oxide films,noble metal supported carriers,etc.;At the same time,the band gap width of SrTiO₃ is 3.2 eV,which responds to ultraviolet light.Due to its high catalytic activity,photochemical properties and optical stability,SrTiO₃ is also used in photocatalytic degradation,photocatalytic water to produce hydrogen,etc.Because a single SrTiO₃ material is used as a catalyst,the catalytic field,catalytic activity,and catalytic life are all limited.Therefore,in order to solve this problem,SrTiO₃ is usually modified to improve its catalytic activity and widen its application range.In the work,we used interface chemical reaction method and impregnation reduction method to prepare metal-strontium titanate heterojunction materials and solid-phase synthesis method to prepare up-conversion strontium titanate materials,and applied research on catalytic hydrogen production from formaldehyde,photodegradation,and hydrogen production from photolysis water.The research contents of this work are as follows:SrTiO₃ nano-blocks were prepared by solid-phase synthesis,and SrTiO₃@Pd nano-heterojunction materials were prepared by interfacial chemical reaction method and impregnation reduction method at room temperature,and then catalyzed formaldehyde to hydrogen production at room temperature.It turns out that the factors affecting the rate of hydrogen production are these conditions,which are the initial formaldehyde concentration,initial NaOH concentration,Pd loading amount in SrTiO₃@Pd and temperature.The 5 wt%SrTiO₃@Pd prepared by the interface method had the best catalytic activity,and the best average hydrogen production rate was 148.81mL/min*g.SrTiO₃:Yb³⁺,Tm³⁺up-conversion nanomaterials were prepared by solid-phase synthesis,and SrTiO₃:Yb³⁺,Tm³⁺@Ag nano-heterojunction materials were prepared by interfacial chemical reaction method and impregnation reduction method at room temperature.Then,as light source by UV,Xenon and 980nm lamp,carbamazepine（CBZ）or malachite green（MG）pollutants have been photodegraded by SrTiO₃:Yb³⁺,Tm³⁺@Ag.The results show that the prepared up-converted nanomaterials can respond to near-infrared light.The photodegradation efficiency is profoundly influenced by the facters,which are target pollutants and catalyst,Ag loading in SrTiO₃:Yb³⁺,Tm³⁺@Ag,pH and oxidant.The mechanism of photodegradation was explored through free radical capture experiments.The results show that the active species,which promote photodegradation of CBZ or MG,are both photogenerated holes（h⁺）,hydroxyl radicals（·OH）and Superoxide radical(?O^2-).Up-converting SrTiO₃:Yb³⁺,Tm³⁺nanomaterials prepared by solid-phase synthesis,photocatalytic decomposition of water to produce hydrogen under the light source of ultraviolet lamp,xenon lamp,and 980nm laser.The results show that the prepared SrTiO₃:Yb³⁺,Tm³⁺upconversion nanomaterials have a higher hydrogen production rate than pure SrTiO₃,and can achieve photolysis of hydrogen in the near-infrared region under the irradiation of a 980nm laser,the average hydrogen production rate was 15.68μmol·g^-1·h^-1.In summary,the modified strontium titanate material has good catalytic activity and stability in the fields of hydrogen production from formaldehyde,photodegradation,and hydrogen production from photolysis of water.Simple preparation process of derivatives based on SrTiO₃and has broad application prospects in the field of catalysis.