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Investigation On The Reaction Process Of Photocatalytic Water Splitting For Hydrogen Evolution Over CuO/TiO2

Posted on:2017-04-09Degree:MasterType:Thesis
Country:ChinaCandidate:X YangFull Text:PDF
GTID:2321330518993105Subject:Engineering
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Exploiting photocatalysts with highly activity,increase solar photocatalytic quantum yield and the promotion of industrialization has become a hot issues in the field of photocatalysis,this can solve future energy crisis and reduce environmental pollution.Nanosized TiO2 is currently the most widely studied a photocatalyst has some advantages including chemically stable,non-toxic,pollution,etc.,especially in the field of photocatalytic water splitting for hydrogen evolution research has shown excellent performance,however,nanosized TiO2 has the drawbacks of low reaction rates and poor utilizationutilization of solar energy absorption and which hinder its photocatalytic spread.In this paper,TiO2(P25)was used as the substrate to be modified with CuO,composite semiconductor CuO/TiO2 photocatalysts were synthesized.Detailed research on the reaction process of photocatalytic water splitting for hydrogen evolution and CuO/TiO2 photocatalyst mechanism of decomposition of water into hydrogen were established.The main research work are summarized as follows:(1)CuO/TiO2 composite photocatalysts were synthesized through a impregnation and thermal decomposition route,the TiO2(P25)to uniformly disperse Cu(NO3)2·3H2O aqueous solution and dried,calcined.The samples were characterized by the X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),UV-visible diffuse reflectance spectroscopy(UV-vis).The results show the success of CuO supported on the catalyst surface,the catalyst morphology similar to spherical,composite semiconductor CuO/TiO2 photocatalysts extended from the absorption wavelength of 412 nm to 432 nm,compared to the band gap width and P25 decreased from 3.01 eV 2.87 eV,visible light absorption range to expand and possesses enhanced optical absorption property.(2)Studied on the reaction process of photocatalytic water splitting for hydrogen evolution over composite semiconductor CuO/TiO2 photocatalysis,investigated linear alcohols and polyols structure as a sacrificial agent photocatalyic water splitting for hydrogen evolution results were analyzed.The effect of CuO loading,photocatalyst amount,the initial concentration of the ethylene glycol,light wavelength,light area solution on the reaction rate of H2-evolution photoactivity was studied.The results show when loading CuO was 1.0 wt%,the amount of photocatalyst 0.08 g/100 mL solution,glycol initial concentration of 7.2 mol/L,the optimal hydrogen evolution rate reachs 604.5 ?mol·h-1·g-1 under UV light.Calculate the photocatalytic water splitting for hydrogen evolution energy conversion efficiency and quantum yields were 1.85%and 4.24%.(3)According to the experimental analysis of the photocatalytic reaction liquid product results,theoretical arguments photocatalytic water splitting for hydrogen evolution reaction mechanism.Composite semiconductor CuO/TiO2 photocatalytic water splitting for hydrogen evolution reaction mechanism as follows:the results showed that the CuO supported on TiO2 surface on the reaction process of photocatalytic water splitting,the conduction band occurs migration which occurred in the reduction reaction generates a trace of Cu2O.We suggest that ethylene glycol as electron donor may be further oxidized via glycolic acid on the valence band,the final product was CO2 and H2O.
Keywords/Search Tags:photocatalysis, water splitting, hydrogen evolution, ethylene glycol, CuO/TiO2 band gap width, redox
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