Research On The Preparation Of Doped Composite Semiconductor Photocatalyst Response To Visible Light And Its Photocatalytic Performance

In this thesis the preparation of doped composite semiconductor photocatalyst as well as its photocatalytic performance for hydrogen production was searched. The reseach works is composed of two parts:The first part was the study on the preparation of CdS-SiO₂ and its photocatalytic performance. CdS nanoparticle was prepared by deposited method with CdSO₄ and Na₂S. Pt was loaded onto CdS by photodeposition method. Pt-CdS-SiO₂ was synthesized via hydrolysis of tetraethylorthosilicate in the presence of Pt-CdS. The samples were characterized by XRD, BET, PL and UV-Vis techniques. The photocorrosion of various CdS samples were monitored by measuring dissolved Cd²⁺ using an electrochemistry method. The photocatalytic activity of Pt-CdS-SiO₂ for hydrogen evolution was investigated in aqueous formic acid solution under visible light irradiation (λ=420nm). The results indicated that the photocorrosion and coalescence of CdS nanoparticles were prevented effectively by coating SiO₂, and the separation of photogenerated electron-hole pairs was promoted, so the stability and activity of SiO_-Pt-CdS was improved.The second part was the study on the preparation of CdS/La³⁺-TiO₂ and its photocatalytic performance. CdS nanoparticle was prepared by deposited method with CdSO₄ and Na₂S.And the catalyst of CdS/La³⁺-TiO₂ was gained by sol-gel method. The samples were characterized by XRD, UV-Vis and an electrochemistry method. The photocatalytic activity of CdS/La³⁺-Ti02 for hydrogen evolution was investigated in aqueous Na₂S and Na₂SO₃ solution under visible light irradiation (λ=420nm). The effect of composite amount and doping amount for the catalysts were analyzed. The results indicated that the doped composite photocatalyst has better visible-light photocatalytic properties than single catalyst because the absorption of visible-light was improved.