| With the development of economy, environmental problem increasingly prominent, people all over the world are becoming more and more attention to the environment. Semiconductor photocatalysis used in pollution control is the most active research areas. Especially, the TiO2is the most popular with the scientists from all over the world. Due to the stability of TiO2chemical and photochemical properties, low cost, easy recovery, acid and alkali resistant, non-toxic, good high catalytic activity, as well as the advantages of strong oxidizing and reducing, TiO2has recently been recognized as a promising material for photochemical applications. However, TiO2has a bandgap about3.2eV, only the high energy ultraviolet light can been absorbed for photocatalytic reactions, while the visible light can’t be used. And the recombination of the electron hole pairs generated by photon in TiO2photocatalysis is easy, the production of quantum rate is low. Therefore, the TiO2photocatalysis was largely limited in practical application, thus, the modification of TiO2to improve the utilization of visible light in sunlight is still a very promising project.To solve the frontier problem of science and technology in the field of solar photocatalysis, we have modified the TiO2by two strategys to improve the performance of photocatalysis under sunlight.The one method:TiO2nanostructure arrays were fabricated by hydrothermal method using high purity titanium plate as titanium source, then the precious metals gold naoparticles were deposited on TiO2, finally the narrow semiconductor CdS was in-situ grown on the Au surfaces, so the ternary TiO2/Au/CdS heterojunctions nanoarrays was formed. The structure and properties of TiO2/Au/CdS heteroj unctions nanoarrays have been characterized using XRD. SEM. photoluminesence spectra, and UV-visible light absoption spectra. The effects of preparation conditions on the structure and photocatalytic activity of TiO2photocatalyst have been studied systematically. The results showed that the performance of ternary TiO2/Au/CdS heterojunction photocatalysts under visible light is highly efficient. The visible light response characteristics of ternary photocatalysts bave been improved by the narrow bandgpap semiconductor CdS. The electrons and the holes generated by photon are located CdS and TiO2, due to the directional migration of charge transfer in the ternary TiO2/Au/CdS heteroj unction, which can effectively inhibit the recombination of the electon hole pairs and improve the conversion efficiency of solar energy. And the problem of recovery and recycling in nanomaterials photocatalysis applications have solved by the array structures.The another method:the TiO2was prepared by a hydrothermal method using tetrabutyl titanate as titanium source. The structure and properties of TiO2/r-GO photocatalysts have been characterized using SEM, photoluminesence spectra, and UV-visible light absoption spectra. The effects of preparation conditions on the structure and photocatalytic activity of TiO2photocatalyst have been studied systematically. The results showed that the performance of TiO2/r-GO photocatalysts under UV light is higher efficient than that of pure TiO2photocatalysts. Under the UV light, the transfer of the electrons generated by photon on TiO2to the r-GO, through the TiO2/r-GO interface has reduced the probability of recombination of photogenerated electron hole pairs, lead to the higher photocatalytic activity. Through the modification of TiO2/GO by the second method, under ultraviolet light, the decomposition rate and efficiency of methyl orange was obviously higher than that of pure TiO2, it is because the graphene oxide increase specific surface area of the pure TiO2, but also can transfer electron-hole.This study initial revealed theoretically the mechanism of the theoretically reactions, and provided a theoretical basis for a new photocatalytic technology with the effective use of solar light, brought great economic value and social significance. |
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