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Prepartion Of Up-conversion Luminescence Agent/TiO2-Ta2O5/Cocatalyst Composite Catalyst And Study On Visible Light Photocatalytic Hydrogen Production From Water Splitting

Posted on:2018-12-03Degree:MasterType:Thesis
Country:ChinaCandidate:S N WeiFull Text:PDF
GTID:2321330512998940Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Semiconductor photocatalytic water splitting technology occupies a place in new energy field.As an excellent semiconductor material,titanium dioxide?TiO2?,due to its chemical stability,insoluble in water,good corrosion resistance of the esuperior performance has favored by researchers.Nevertheless,TiO2 as a photocatalyst still has some drawbacks.Firstly,TiO2 has higher electron hole recombination rate,which lead to efficiency of hydrogen production are not carried out as expected,and much fetter in it application.Secondly,because of relatively higher band gap level?Eg = 3.2 e V?,it can be activated by ultraviolet-light with high-energy to carry out the photocatalytic reaction.However,ultraviolet-light accounts for less than 5.0 % of the sunlight result in the hydrogen production activity of TiO2 was none too high under sunlight irradition.Thence,separating photogenerated electron-hole pairs of TiO2 and enhancing the utilization rate of TiO2 for sunlight is one of the focus areas of hydrogen production from water splitting.Tantalum pentoxide?Ta2O5?is another excellent semiconductor catalyst,it has been considered to be almost comparable to the landmark photocatalyst of TiO2 owing to its excellent optical properties characteristic.TiO2 combine with Ta2O5 to form a putative recombination center between valence band?VB?of Ti O2 and conduction band?CB?of Ta2O5 due to their similar potentials under visible-light irradiation.Thus,the holes in VB of Ta2O5 and electrons in CB of TiO2 are completely separated.Forthemore,the photocatalytic hydrogen generation activity of TiO2 was notable improved.In recent years,some researchers put forward the report on the photocatalytic hydrogen generation for water splitting by using TiO2 combined with up-conversion luminescence agents and has made certain achievements.This is due to the fact that the up conversion luminescent material can convert the low energy visible-light to the high energy ultraviolet-light,which excite TiO2 and Ta2O5 to broaden the scope of their absorption spectra so that further enhance the photocatalytic activity.Up to now,there is also a factor that the photogenerated electrons/holes are easily consumed via recombination restricting the photocatalytic hydrogen evaluation.If further enhance the ammount of photocatalytic hydrogen production,still need to find a way to promote the rapid surface transfer of photogenerated electrons and holes from photocatalyst for hydrogen production and sacrificial agent consumption respectively.In this paper,a series of experiment were investigated about the photocatalytic hydrogen production performance of Ti O2.Through the combination of other wide band gap semiconductor and adding up-conversion luminescence agent and cocatalyst,many novel catalytic materials,Er3+:Y3Al5O12/TiO2-Ta2O5/MoO2 composite membrane and Au/(TiO2-Fe3+?V5+-Ta2O5)/Er3+:YAlO3 nanocomposite,were successfully prepared.The prepared catalyst were characterized by PL,SEM,TEM,XRD,EDX and FTIR.UV-vis and PL of Er3+:Y3Al5O12 and Er3+:YAlO3 were also characterization.In addition,some influential factors on the photocatalytic hydrogen production were investigated in detail,such as TiO2 and Ta2O5 molar ratio,heat-treated temperature,heat-treated time and reusability of the photocatalyst,etc.Through the research of compound materials mentioned above.We found that compositing with another wide-band semiconductors and loading up-conversion luminescent material and cocatalyst onto the photocatalyst can provide a reference for visible-light photocatalytic water splitting for hydrogen evaluation.Perhaps,it provides a possible for large-sale hydrogen production using solar energy in the future.
Keywords/Search Tags:Up-conversion luminescence agent, TiO2-TTa2O5 composite, Composite membrane, Visible-light photocatalytic hydrogen production, Water splitting
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