Preparation Of Sulfide Semiconductor Heterojunction/Polysulfone Fiber Composite And Photocatalysis Of Hydrogen Evolution

In this paper, carboxylic polysulfone fiber mats with nano-micro sizeinterconnected open pore structure and good anti-degradation under irradiationwere prepared by electrospinning process. It was used as a carrier for sulfidesemiconductor heterojunction photocatalyst which was prepared by hydrothermalmethod. Photocatalytic performance and stability was studied under ultra-violetirradiation and visible light irradiation. The main contents were as the following:（1） Electrospun ability of polysulfone resin and processing parameters werestudied systematically. It showed that the viscosity of polymer solution played animportant role in electrospinning ability. The mixed solvent volume fixed at25mL,uniform fibers were obtained when the amount of polyethersulfone （PES） andpolyphenylsulfone （PPSU） was5.0g and5.5g, respectively. For PES/PPSU system,uniform fibers were prepared when the amount of was5.5g, PPSU in the systemwas10wt%. Mixed solvent of different boiling points was used to improve theelectrospinning ability of the polysulfone. The best ratio of mixed solvent wasN-methyl-2-pyrrolidone （NMP）: acetone=6:4.（2） Polysulfone fiber mats were modified by carboxylization. It showed that:ternary system styrene-maleic anhydride copolymer （SMA）/PES/PPSU boastedbetter electrospinning ability than binary SMA/PES. Amount of SMA determinedwhether photocatalysts could be loaded on the fiber mat. With low quantity of SMA,carboxyl content was too small to coordinate metal ions. For ternary system, whenPES/PPSU was5.0g, the amount of SMA had to be at least0.5g.（3） Using polysulfone fiber composites as carriers, the ZnS/TiO₂core/shellheterojunctions were immobilized on the surface of carriers. The composites werecharacterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）,electron spectrum （XPS）, transmission electron microscope （TEM）, ultravioletvisible diffuse reflectance spectrum （UV-VIS） and thermogravimetric analysis（TGA）. TEM image indicated that the surface of polymer fibers were covered byZnS particles, the slightly agglomerated TiO₂particles were grown on the surfaceof ZnS particles, which revealed that ZnS/TiO₂heterojunction was successfullyfabricated on the surface of polymer fibers. UV-VIS analysis show that the absorption spectra of composites are mainly in the UV region. Photocatalytichydrogen production experiment was run using mercury lamp irradiation. Theresult showed that the photocatalytic ability of ZnS/TiO₂heterojunction/polysulfone fiber composites was better than that of ZnS/TiO₂particles, which also boasted good recycle ability and great stability. The averagerate of H2evolution achieved15mL/h in the third run.（4） Using polysulfone fiber composites as carriers, the SnS₂/TiO₂andSnS/TiO₂core/shell heterojunctions were immobilized on the surface of carriers.TEM image indicated that the surface of polymer fibers were covered by SnS₂particles, the slightly agglomerated TiO₂particles were grown on the surface ofSnS₂particles, which revealed that SnS₂/TiO₂heterojunction was successfullyfabricated on the surface of polymer fibers. UV-VIS absorption spectra showed thatthe composites had absorption in the visible range. Photocatalytic hydrogenevolution experiment was run using Xenon lamp simulated as sunshine. The resultshowed that in three reaction cycles, the photocatalytic ability of SnS₂/TiO₂heterojunction polysulfone fiber composites was better than that of SnS₂/TiO₂particles, which also boasted good recycle ability and great stability. The averagerate of H2evolution was6.5mL/h in the third run.