Preparation And Photocatalytic Application Of Metal Sulphide Semiconductor Modified Or Sol-gel Fixed TiO₂ Nanofibers

Photocatalysis, as a clean, economical, environmentally friendly technique, offers a great potentical for water protection. Titanium dioxide(Ti O 2), as one of intensively used photocatalytic materials, arouses concerns due to its advantages: excellent physical and chemical stability, non-toxic, and low cost. However, Ti O2 still has some limitations: wide band gap only for UV light utilization, high electron-hole recombination rate, and difficult recycle. In order to solve the issues, this thesis focuses on two sides:(1) the modification of Ti O2 nanofibers by using narrow band gap metal sulphide solid solution through hydrothermal method. The composites have efficient light utilization and high photocatalytic activity.(2) Ti O2 nanofibers are fixed by sol-gel method, solving the problem of recycle for catalyst. The main research contents are as follows:(1) Preparation and characterization of hierarchical architectures of Zn S-In2S3 solid solution onto Ti O2 nanofibers: Ti O2 nanofibers(Ti O2 NFs) were prepared by electrospinning technique and then Zn S-In2S3 solid solution was grown onto the surface of the porous Ti O2 NFs by hydrothermal method, getting a trinary composite material(Ti O2@Zn S-In2S3). The Zn S-In2S3 solid solution nanostructures not only uniformly grew on the surface of Ti O2 nanofibers, but also formed heterostructures with Ti O2 NFs.The new heterostructures ont only exhibited excellent visible light response but also effectively inhibited the recombination of photogenerated electronic-hole pairs.(2) Photocatalytic degradation of dye rhodamine B on Ti O2@Zn S-In2S3 composites: As one of the environmental refractory organic pollutants, dye rhodamine B(Rh B) was chosen for investigating the photocatalytic performance of the catalyst. The adsorption performance tests showed that the Ti O2@Zn S-In2S3 heterostructures had a high adsorption capacity of 72.51 mmol/g. That was due to its large specific surface area which could offer more adsorption sites. Under visible light irradiation, the Rh B photocatalytic degradation rate over Ti O2@Zn S-In2S3 heterostructures was about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure Ti O2 nanofibers, Zn S nanoparticles, In2S3/Ti O2 nanofibers, Zn S/Ti O2 nanofibers, and Zn S-In2S3 solid solution, respectively.(3) Fabrication, characterization and photocatalytic application of sol-gel nanoglues for an organic binder-free Ti O2 nanofibers: One-dimensional(1-D) Ti O2 nanofibers(NFs) prepared by electrospinning were constructed onto the surface of a Ti O2 nanotube(NTs) arrays via sol-gel method, getting a novel composite Ti O2 NF/Ti O2 NTs. The Ti O2 NF/Ti O2 NTs showed increeased light absorption and better electronic transmission efficiency. Rh B was used as target pollutant and the photodegradation experiment was assessed under simulated sunlight. The results showed that the degradation efficiency of Rh B over Ti O2 NF/Ti O2 NTs reached 95.32% in 120 min. In addition, the degradation efficiency of Ti O2@Zn S-In2S3 heterostructures still reached 90.14% after five repeated experiments, indicating a good performance of recycle.