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Study On The Synthesisand Photocatalytic Property Of A-WO3for Water Decomposition (A=CuCrO2,CuCrxAl1-xO2x=0.1-0.9)

Posted on:2015-04-20Degree:MasterType:Thesis
Country:ChinaCandidate:X P LiuFull Text:PDF
GTID:2181330452465810Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
With the development of society, large amounts of energy are consumed. It hasbecome an urgent task for the future to research and develop a clean, abundant, sustainablenew energy without pollution. While hydrogen is one of the most ideal new energies, andphotocatalytic decomposition of water to hydrogen under solar is the most environmentalfriendly method to obtain hydrogen.Delafossite CuCrO2was prepared by various synthetic methods such as semi-wet,sol-gel and combustion using Cr(NO3)3and Cu(NO3)2as raw material. The samplesprepared by different methods were characterized by using X-ray diffraction (XRD),ultraviolet-visible diffuse reflectance (UV-vis DR), scanning electron microscope (SEM).The photocatalytic hydrogen producing of CuCrO2under xenon lamp and mercury lampirradiation was also evaluated. The results showed CuCrO2prepared by solutioncombustion reaction method has advantages of smaller particle size, uniform dispersion,stronger ultraviolet absorption effect and higher photocatalytic activity under mercury lampirradiation. The effects of fuel type and the amount of fuel on the phase composition,morphology, light absorption property of the as-synthesized products were systematicallystudied. The results showed CuCrO2with small particle and good photocatalytic propertywhen using glycine as fuel and the ratio of glycine and metal ions is1.4:1.The composite photocatalyst CuCrO2-WO3was successfully prepared by mechanicalgrinding and heat-treatment. The factors of calcination temperature, calcination time,composite ratio and pH of grinding media of CuCrO2-WO3were investigated. The resultsshow that the optimal photocatalyst is prepared withnCuCrO2:nWO31:0.9by calcination at450℃for3.5h, and the photocatalytic activity is further enhanced when the pH ofgrinding media at8. Ru loading as cocatalyst also remarkably enhanced the photocatalytichydrogen producing. The0.5wt%Ru/(CuCrO2-WO3) exhibited better photocatalyticactivity for splitting pure water into hydrogen under300W xenon lamp irradiation, onwhich H2production was about10μmol for3h.A series of CuCrxAl1-xO2solid solution were prepared by sol-gel method usingCu(NO3)2, Cr(NO3)3and Al(NO3)3as raw material. A study on the samples were carried outthrough XRD, UV-vis-DR, SEM. Composite photocatalyst of CuCrxAl1-xO2-WO3was synthesized, and the photocatalytic hydrogen producing were evaluated based on the H2production under250W mercury lamp. XRD results showed that with the increase of x,the diffraction patterns peak of as-synthesised products appeared migration and abateregularly, so it verified that they were not the mixtures of CuCrO2and CuAlO2. UV-vis-DRresults showed that with the increase of x, solid solutions absorption edge red shiftgradually and forbidden gap decreases. The photocatalytic activity of the catalystsshowed that CuCrxAl1-xO2-WO3all have activities, the activities of CuCr0.5Al0.5O2-WO3were better. Ag or Ru loading as cocatalyst also remarkably enhanced the photocatalytichydrogen producing. But the photocatalytic activity of the composite photocatalystCuCr0.5Al0.5O2-WO3is inferior to CuCrO2in general.
Keywords/Search Tags:photocatalysis, water splitting, hydrogen production, solid solution, composite catalyst
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