Preparation,Modification and Application of High Efficient TiO2 Based Photocatalysis

Author:Shang Zuo Zuo

Supervisor:tan xin

Database:Doctor

Degree Year:2017

Download:65

Pages:157

Size:6292K

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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.