Doped Modification Of Sulfide Photocatalysts And Its Photocatalytic Water Splitting For Hydrogen Evolution Performance Under Visible Light

In this thesis, the effects of ion doping on photocatalytic hydrogen evolution over sulfide photocatalysts from aqueous solution containing Na2S and Na2SO3as a electron donor were researched. The possible mechanisms were discussed. The research work mainly consists of three parts.In the first part, the effects of Bi3+doping on photocatalytic hydrogen evolution over CdxZn1-xS photocatalysts were researched. The influencing factors in photocatalytic reaction were optimized and the reaction mechanism was discussed. Bi3+doped CdxZn1-xS photocatalysts were prepared by hydrothermal method, Bi(m)/CdxZn1-xS were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), energy dispersive X-ray spectroscopy (EDX), UV-Vis absorption spectroscope (UV-Vis), BET and electrochemistry method techniques. The results showed that when at the preparation temperature160℃, x=0.5,4wt%Pt-loaded Bi(m)/CdxZn1-xS exhibited the highest photocatalytic activity. When Bi3+doping content is lower, the doping ions lie at the surface lattice sites, whereas when the doping content is higher, the ions also enter the bulk lattice sites. When the Bi3+doping content is0.1mole%, the photocatalyst exhibits the highest activity and the average apparent quantum yield amounts to9.71%during30h irradiation. The modification of Bi3+doping can efficiently depress the recombination of electron and hole.The second part investigated the effects of Ru3+doping on photocatalytic hydrogen evolution over Cd0.5Zn0.5S photocatalysts and the reaction factors of hydrogen evolution were studied. The possible mechanism was also discussed. CdxZn1-xS and Ru3+doped Cdo.5Zno.5S photocatalysts were prepared by hydrothermal method, and characterized by XRD, UV-Vis and electrochemistry techniques. The results indicated that Ru3+doping enhanced photocatalytic activity markedly. When At the doping content0.1mole%, the reaction temperature160℃,3wt%Pt-loaded photocatalysts has the highest activity. It should be attributed to the formation of doped level and defects which enhanced the absorption of catalysts in visible light and depressed the recombination of electron and hole.The third part studied on the influences of photocatalytic activity of CdS by Bi3+-doping and the optimizing factors of hydrogen evolution. The possible mechanism was also researched. CdS and Bi3+doped CdS photocatalysts were prepared by hydrothermal and immersion method. The photocatalysts were characterized by XRD, UV-Vis, TEM, BET, PL and electrochemistry techniques. It was found that Bi3+doping enhances markedly photocatalytic activity of CdS under visible light irradiation (λ≥420nm). the photocatalyst exhibits stable hydrogen evolution performance during30h irradiation. The reason is that electronegativity of Bi is higher than Zn and Cd, which can trap e-more effectively to decrease charge-carrier recombination and Bi3+doping can promote Pt photodepositon.