| photocatalytic activity, morphology and mechanism of semiconductor composite photocatalysts were studied in this paper. Ti O2/Zn O composite photocatalysts which owned high crystallinity and well-defined morphology were prepared by joint method of hydrothermal and sol-gel, then characterized by XRD, TEM, UV-Vi S, BET. At the same time, the photocatalytic activity of Ti O2/Zn O composite was evaluated by photocatalytic degradation of methyl orange under UV illumination. Ti O2 narorods film was synthesized by hydrothermal method, and also was used as matrix to prepare the composites film, such as Ti O2/Cd S and Ti O2/Zn O film. The samples were studied by SEM, XRD, UV-Vi S to explore the growth mechanism and other properties of composites film. The law of electron transfer between the different component among semiconductor composites photocatalyst system has been studied through using classical Ti O2/Cd S system and Ag orientation deposition. However, the difference of solubility product between different sulfide resulted in failure, then lesson and experience were concluded. Subsequently, heterojunction theory was used to explain the high catalytic activity of semiconductor composites.Ti O2/Zn O composite photocatalysts with various mole ratio of Zn O(Ti O2/Zn O, Ti O2/25% Zn O, Ti O2/50% Zn O) have been prepared by joint method of hydrothermal and sol-gel, XRD, BET, TEM and UV-Vi S characterization showed that the composites have high crystallinity and well-defined morphology. Among these composites, photocatalytic activity of all composites has been higher than pure Ti O2, but the ativity of composites with 100% and 50% mole ratio Zn O has been lower than pure Zn O and Ti O2/25% Zn O has best activity, and this phenomenon was explained by heterojunction theory.FTO was used as matrix to prepare rutile nanorods film. Ti O2/Cd S composites film and Ti O2/Zn O composite film by hydrothermal approach. As for pure Ti O2 nanorods film, the films with different arrangement mode of nanorods has been synthesized owning to different way of FTO placing, which the reason was analyzed. The Cd S nanoparticles decorating Ti O2 film turned into nanorods gradually over heating time and this composites film could be responsive to visible light. Zn O on Ti O2 was composed of cotton-shaped nano-flake. With the time increasing the Zn O appeared to be sponge until it covered Ti O2 film completely. At the end, hexagnol Zn O particles has appeared and scattered on the surface.Heterojunction theory and experimentation by use of classical Ti O2/Cd S system both have been applied to explain the reason why composite photocatalyst owned high photocatalytic activity. firstly, the site on which Ag will deposit on between Cd S and Ti O2 could judge the direction of electron transfer, and then the phenomena of high photocatalytic activity was expounded. However the huge difference of solubility product between Cadmium Sulfide and Silver Sulfide has leaded to failure. Subsequently according to heterojunction theory, an internal electrostatic filed built in heterojunction area could separate the electrons and holes excited by light and restrain the carries recombination, then came to high activity. |
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