| The development of science and technology makes people’s demand for energy increasing year by year. The problem of limited reservation and pollution of fossil energy lead to urgent demand for new energy. Photocatalytic technology can use semiconductor materials to convert the solar energy into chemical energy for decomposition of water into hydrogen and degradation of pollutants, with advantages of strong oxidation, simple reaction condition, good repeatability, high efficiency. Titanium dioxide is one of the most popular photocatalyst, but its disadvantages such as wide band gap, low utilization efficiency of sunlight, difficult operation of catalyst powder, hard recovery limit its application. So research on semiconductor photocatalysts with high photocatalytic activity and easy operation has significance of theory and application for large scale application.In this paper, carboxyl group containing electrospun fiber mats of PVDF/SMA/, graphite were used as carriers, the semiconductor materials were loaded onto the fiber surfaces through complexation adsorption of carboxyl group to metal ions in hydrothermal solution, that series of TiO2 based heterojunction (PVDF/SMA/graphite) fiber composite photocatalysts were prepared. Experiments on photocatalytic hydrogen production from water decomposition under visible light were studied to explore the factors and mechanism affecting the photocatalytic efficiency of these fiber composite photocatalytics. The main research contents include the following four aspects:(1) Preparation of TiO2@FeOOH/(PVDF/SMA) fiber composites:the PVDF/SMA electrospun fiber mats were used as carriers, FeOOH/(PVDF/SMA) fiber composites and TiO2@FeOOH heterojunction/(PVDF/SMA) fiber composites were prepared under hydrothermal condition at 85 ℃. The FeOOH coated on the surface of fluorocarbon polymer fibers are needle crystals, TiO2 were granular crystals grown around FeOOH in the prepared composite fibers with absorption in 300-535 nm region. Degradation experiments for methyl orange under Xenon lamp simulated sunlight showed that: methyl orange can be degraded up to 2.04% under 2 h visible light with TiO2@FeOOH heterojunction/(PVDF/SMA) composites as photocatalytic, which is 3.2 times efficiency of Degussa P25 TiO2 and 1.5 times that of TiO2@FeO0H powder. Experiments of hydrogen production from water decomposition under Xenon lamp simulated solar and photocatalytic showed that:TiO2@FeOOH heterojunction /(PVDF/SMA) composite fibers have nice repeated photocatalytic ability with maximum hydrogen production rate up to 769 μmol·h-1·g-1cat.(2)Preparation and photocatalytic performance of different sulfides-TiO2 heterojunction conductive fluoropolymer fiber composites. The conductive electrospun fiber mats based on PVDF/SMA/graphite were used as carriers, different chalcogenides TiO2 heterojunctions were loaded onto the fibers by hydrothermal reaction. That CdSe@TiO2 heterojunction/conductive fluorocarbon polymer fiber composites, TiO2@SnS2/ (PVDF/SMA/graphite) fiber composites, TiO2@CdS/ (PVDF/SMA/ graphite) fiber composites were prepared, while TiO2 were sharp titanium crystals in all. Experiments of hydrogen production from water decomposition under xenon lamp simulated solar showed that:the conductive fiber as carriers have better effect on improving photocatalytic efficiency than that of nonconductive fibers, CdSe@TiO2/ (PVDF/SMA/graphite) composites show highest photocatalytic activity in different heterostructures, TiO2@CdS heterojunction/(PVDF/SMA/graphite) fiber composite is latter, while TiO2@SnS2 heterojunction/(PVDF/SMA/graphite) fiber composite has lowest photocatalytic activity.(3) Sn doped CdS and TiO2 were loaded onto (PVDF/SMA/graphite) fiber composites by Sn ion doping under hydrothermal synthesis, that TiO2@Sn doped CdS/ (PVDF/SMA/graphite) fiber composites were prepared. It shows nice photocatalytic activity in the process of photocatalytic hydrogen production from water, the average hydrogen production rate is 2885 μmol·h-1·g-1cat, which is 1.4 times higher efficiency than that of nonconductive fiber carriers, and 3.86 times of fiber composites without Sn doping.(4) CdS@Cl-TiO2/ (PVDF/SMA/graphite) fiber composite was prepared through Cl ion doping. It shows narrowest band gap when Cl atoms content in TiO2 is 0.45%. Xenon lamp simulated sunlight photocatalytic hydrogen production from water decomposition tested that, CdS@Cl-TiO2/(PVDF/SMA/graphite) fiber composites have ability of photocatalytic hydrogen production with average speed of 3260 μmol·h-1·g-1cat, which is better than that of conductive fiber without Cl doping, and have good repeating utilization. |
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