Fabrication Of Zeolite-loaded Tio₂-cds Composite Semiconductor For Photocatalytic Production Of H₂

The photocatalytic production of H2 is a combinative technology of environmental treatment and cyclic utilization of resource. The key technology mainly focuses on the development of catalysts with strong visible light response, high photo-catalytic efficiency and the long lifetime.In view of the disadvantages of easy condensation, low quantum yield, low utilization of light in TiO₂ power, and easy photo-corrosion in bulk CdS , We used sol-gel method to prepare zeolite loaded TiO₂ photocatalyst, prepare zeolite-loaded CdS by ion exchange and precipitation method, and combining these two methods to prepare zeolite loaded TiO₂-CdS photocatalyst. The effects of the preparation conditions, such as calcination temperature, ratio of sol and zeolite and exchange times were investigated. The structure and physicochemical properties were characterized by UV-Vis diffuse reflection spectra, XRD, FT-IR, ICP-AES and SEM-EDS. The performance of photocatalytic production of H2 over the above photocatalysts under high pressure mercury lamp and xenon lamp were also studied.It was known from the characteristic results that zeolite loaded TiO₂ was better when calcined at 400℃, the ratio zeolite and sol was 1g zeolite / 5ml sol, in which TiO₂ was anatase, and the introduction of TiO₂ changed the surface morphology of zeolite. In the zeolite loaded CdS system, CdS was hexagonal structure, a blue shift of the adsorption edge in UV-Vis diffuse reflection spectra by quantum size effect, and exchange times was two best. A red shift of the adsorption edge in UV-Vis diffuse reflection spectra of zeolite loaded TiO₂-CdS, in which emerged a new peak corresponding to CdS. TiO₂ was anatase and rutile crystal co-exist, and CdS have not crystaled, but rather dispersed in zeolite pore or scattered on the sample surface.The zeolite loaded CdS photocatalyst could prevent electron-hole from recombination and enhance the efficiency of H2 evolution, so it could improve the stability of photocatalyst. After CdS loaded on the zeolite/TiO₂, hydrogen output has been enhanced largely, indicating TiO₂ and CdS composited together, which could complement each other, and increase the hole-electron separation efficiency. The amount of hydrogen under high pressure mercury lamp reached 2000μmol/g,2300μmol/g and 2200μmol/g over zeolite loaded TiO₂,zeolite loaded CdS and zeolite loaded TiO₂-CdS, and the amount of hydrogen under xenon lamp eached 700μmol/g,900μmol/g,and 850μmol/g over zeolite loaded TiO₂,zeolite loaded CdS and zeolite loaded TiO₂-CdS.