| With energy shortages and the increasing pollution of environment, photocatalytic technology was used to solve energy and environmental issues with lots of attentions.Noble metal/semiconductor composite photocatalysts can solve problems in the field of single semiconductor photocatalysts, which the visible light utilization is low,light-generated electron-hole recombination rate is high and photocatalytic efficiency is low. However, there are also many problems in preparation of noble metal/semiconductor composite photocatalysts. In this paper, we aimed at solving this problems, which easily self-nucleation of the second Ag nanoparticles and agglomeration; the noble metal simply loading on the semiconductor surface lead to lost,irreproducibility, instability, corrosion of light; and other issues. The details are summarized as follows:(1) Ag/ZnO arrays composite photocatalysts: moderate viscosity and reduction performance made ethylene glycol a good solvent,which can effectively avoid the self-nucleation of the second Ag nanoparticles and agglomeration. By changing the concentration of AgNO3, the Ag content on the ZnO nanowire arrays can be controllably tuned but no diameter change. Loading Ag can greatly improve the absorption ability of ZnO array in visible light. As a result, when concentration of AgNO3 was 5 mmol/L, the amount of secondary Ag nanoparticles was 0.8%, it can be seen that the photocurrent response of Ag/ZnO arrays was 2.5 times higher than that of pure ZnO arrays. Ag/ZnO arrays had more than twice times faster than ZnO arrays in RhB degradation under the UV-Visible light irradiation. To study of the active species of its degradation, we found that the main active species was hydroxyl radicals.(2) Au doped BiOBr composite photocatalysts: Au doped BiOBr photocatalyst was synthesized by hydrothermal method in the solution with nano gold, KBr and Bi(NO3)3. By changing the concentration of Au solution, the Au doping content can be controllably obtained. The experimental results showed that Au/BiOBr absorption in the visible region was stronger, the initial photocurrent response increased and then decreased when the doping amount of Au increased, the strongest of photocurrent response was 2.5wt%. The visible photocatalytic degradation efficiency of RhB reachedmaximum. the degradation can be roughly completed in 10 min, and it needed 30 min when used pure BiOBr as catalyst. To study of the active species of its degradation, the main active species was holes.(3) Core-shell Au@TiO2 composite photocatalysts: core-shell Au@TiO2 was synthesized by a simple acetone bath method with Au. The results showed that the preparation of sample was prepared with Au, anatase and rutile mixed phase at the calcination temperature of 750°C. Increasing the coating amount of Au, Au@TiO2absorption in the visible region became stronger, the initial photocurrent response would increase and then decrease, the strongest response of photocurrent was 1.0wt%. It was 5times higher than that of pure TiO2. However, the rate of degradation p-nitrophenol increase insignificantly in the UV-Visible light, the degradation of the main active species were superoxide free radical(·O2-) and hydroxyl radical(OH-). The hydrogen production rate of 1.0wt% Au@TiO2 was 10 times higher than that of pure TiO2. This indicates the preparation of core-shell Au@TiO2 is not conducive to degradation p-nitrophenol but in favor of hydrogen production in the UV-Visible light,.(4) Pt/SnXTi1-XO2 composite photocatalysts: In this part, SnXTi1-XO2 catalysts had been prepared by using a sol-gel process. It was used in photocatalytic hydrogen production after plating Pt. Then we explored the effects of photocatalytic hydrogen production properties with the molar ratio of X. According to the final result,we can seen that the material Pt/Sn0.1Ti0.9O2 performed the best efficiency of hydrogen production(106.37 μmol·h-1), which was 2.5 times than Pt/TiO2. Pt/SnO2 was unable to produce hydrogen. |
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