Preparation,Modification And Application Of High Efficient TiO₂ Based Photocatalysis

Due to the high activity,stable chemical properties,economical and non-toxic etc.,TiO₂photocatalyst is recognized as the best photocatalytic material.The three common crystal structures exit in nature are anatase,rutile and brookite.It can be widely used in the fields of organic pollutant degradation,water splitting into H₂,self-cleaning and waste water treatment,which belong to the category of liquid-solid and gas-solid reaction.However,the recombination rate of photogenerated electrons and holes is high,and the band gap?3.2 eV?of TiO₂ semiconductor is wide.Therefore,its application in the practical life is severely limited.According to the defects of low quantum efficiency and narrow light response scope in the field of self-cleaning,gas phase,liquid phase pollutants degradation and water splitting into H₂,we designed three kinds of TiO₂based high efficient nanocomposites by using the specific facets exposed,GR loading and SrTiO₃ hetero-junction methods to improve the photocatalytic activity in their own application.The XRD,SEM,TEM,UV-vis,electrochemical properties and a series of characterization methods were used to explore the working mechanism of material.This provide the basis for desiGRing the high efficient TiO₂ based nanocomposites.Firstly,we prepared the{001}TiO₂/{001}SrTiO₃ epitaxial heterostructures use the direct current facing-target magnetron sputtering method by changing the total work pressure?TWP?.With the increase of TWP,{001}TiO₂ growth on the{001}SrTiO₃substrate on the way of layer-by-layer growth model firstly and then 3-D inland model.The sample prepared at 1.5 Pa shows excellent photoelectrochemical properties and high photoinduced superhydrophilicity.Which can be ascribed to the formation of high quality heterostructure is effective in suppressing the recombination of photogenerated e^--h⁺pairs,and the{001}facets with high surface energy has high oxidation ability.Secondly,the high efficient{001}TiO₂/GR nanocomposit was synthesized use the hydrothermal method by changing the addition of GO and HF.The photocatalytic degradation efficiency?PDE?of the optimal sample?HF:3 mL;GO:18 mg?reached up to 98.7%for liquids methyl orange and up to 78.6%for gaseous toluene under the UV-light irradiation for 30 min,which is much higher than P25.The enhanced photocatalytic properties can be attributed to the excellent electron transport of GR and highly reactive{001}facets can facilitate the separation of photo-generated charge carriers.Moreover,GR can extend the absorption range of light and improve the adsorptivity of pollutant molecules.Thirdly,we synthesized the Ti³⁺modified brookite TiO₂/GR nanocomposites with?211?specific facets exposed successfully,it shows high improved photoreduction activity for water splitting into H₂ with excellent stability.The addition of NaBH₄ could introduce the Ti³⁺and improve the exposure of?211?facts.In addition to promoting the separation of photogenerated e^--h⁺pairs effectively,the mid-gap state was introduced and the absorption ability was improved.