Preparation And Study On The Properties Of Nano Composite Heterojunction Photocatalytic Materials

With the economic and social development, environmental issues have become increasingly prominent, especially water pollution. Particularly semiconductor materials generate electrons with reducing ability and holes with oxidizing ability under irradiation with proper wavelength. Solar energy as an energy source, the use of semiconductor materials to purify water pollutants are the most popular research direction in recent decades. TiO2as a stable, readily available, non-toxic and other advantages to become the topic of most concern as a semiconductor autocatalysis, but because of its a large band gap, low quantum efficiency, and on improving the photocatalytic properties of efforts are constantly being investigated.In this paper, work were launched based on the basic idea of nanocomposites, we use the home-made high-voltage electrospinning equipment was prepared nanocomposites of conducting polymer polypyrrole, TiO2nanofiber, BiFeO3nanofiber, P25were sintered by Spark Plasma Sintering (SPS) technique, carbon-doped rutile TiO2were prepared and its absorption band extended to the visible light. This thesis work has four parts:(1) Combination a homemade electrospinning equipment and in-situ oxidative polymerization successfully prepared PPy/Ag/TiO2ternary composite nanofibers, and a detailed analysis of the structure, optical properties and photocatalytic effect due the this system. We found that coating conducting polymer polypyrrole PPy on TiO2nanofiber which extend its response range to visible light, enhances its visible light photocatalytic effect, and the ternary complex system of photo-generated electron-hole transport mechanism were proposed.(2)1-D composite nanofiber were structured by electrospun in one step, with TiO2and BiFeO3nanoparticles that were synthesized by co-precipitation, the system were constructed based on TiO2matrix, which BiFeO3nanoparticles embedded, confirmed by experiment BiFeO3nano-composite nanofiber composite particles formed inside there are a lot of TiO2and BiFeO3heterojunction formed in the nanofiber were confirmed by s series characterizations, and composite nanofiber significantly expands the range of optical response of TiO2, the highest efficiency proportion is BT10,which has an excellent optical absorption and show a outstanding irradiated current due to its heterojunction which promotes the separation of photo-generated carrier.(3) Combination of electrostatic spinning and previous work on in-situ oxidative polymerization, feeding the simplest precursor to electrospinning BiFeO3nanofibers, constructing core-sheath structure of PPy/BiFeO3composite nanofiber based on in-situ polymerization method, and systematic analysis of structure, morphology comparing PPy/BiFeO3nanoparticles with PPy/BiFeO3nanofibers in visible photocatalytic activity, confirmed nanofibers composites have higher photocatalytic properties under visible light irradiation.(4) Spark Plasma sintering(SPS) technology used to ultrafast heat treatment of P25with low temperature for the first time, the treated P25extend its photoelectric response range to visible light, and degrade organic matter under visible light irradiation effectively, the results confirmed carbon permeate to the interstitial of P25through a series characterizations, inhibiting the recombination of electron-hole obviously, increasing of carrier concentration due to the increasing of the amount of oxygen vacancy.