Synthesis Of Porphyrin/Titanium Dioxide Co-assembly Spheres With Potential Use In Photocatalytic

Development and utilization of solar energy is an effective way to solve the energy and environmental issues. Hydrogen is a chemical energy source which has a series of advantages such as high calorific value, rich source and combustion without pollution. Storage and use of hydrogen energy transformed from solar energy by means of photolysis of water is highly significant. Titanium dioxide is a semiconductor catalyst with excellent electron-hole transmission capacity and widely used in photocatalysis process. However its wide bandgap result that it can just response to ultraviolet light, which greatly reduces the utilization of sunlight. Porphyrin which has strong absorption in visible light range is an important photosensitive material. Therefore it's significative to integrate titanium dioxide with porphyrin to produce co-catalyst which is applied to photocatalytic hydrogen generation.Porphyrin/titania composite is core-shell or surface adsorption structure in general which leads to photo-induced electrons produced by porphyrin can't timely transfer to titanium dioxide and decrease of sunlight utilization. So how to prepare adequately contiguous porphyrin/titania co-catalyst is particularly important. To this issue, we studied the following aspects:1. We got T679/TiO₂ co-assembly sphere with uniform size and good dispersion by assistance of SDS and demonstrated it's random blend structure through element mapping, contrast of TEM image, specific surface area and UV-vis absorption spectrum before and after etched by NaOH. Then we synthesized pure T679 nanosphere and T679@TiO₂ core-shell structure by adjusting experimental conditions and make a contrast about photocatalytic hydrogen production rate of different catalysts. We found that the photocatalytic rate of T679/TiO₂ is much higher than the T679@TiO₂, P25 and pure T679 nanosphere. According to the result we speculated and analyzed the mechanism of photocatalytic hydrogen production and degradation of different structure catalysts.2. We generalized the peristaltic pump slowly injected method to the coassembly experiments of six other kinds of porphyrin with different substituent and central atom and titanium dioxide. We found that the three kinds of porphyrins with benzene carboxyl integrated with titania well but the other three kinds of porphyrins with sulfophenyl group can't form co-assembly sphere from the results of the centrifugation, SEM, FTIR and UV-vis absorption spectrum. Then we made a contrast about photocatalytic hydrogen production rate of the two types catalysts and found the addition of porphyrin make a great contribution to photocatalytic efficiency.