Nanocomposite Fibers Of TiO₂/Metal Sulfide And TiO₂/Noble Metal: Preparation And Study On Photocatalytic Properties

TiO₂ is the most popular oxide semiconductor because of its unique properties such as high physical and chemical stability, non-toxicity, and abundant availability, as well as cost effectiveness. However, TiO₂ is a relatively large band gap semiconductor （Eg = 3.2eV for anatase）, as well-known, that can only be exited by radiation with wavelength below 380nm. Such poor solar light absorption capability is of little practical applications for the TiO₂ photocatalysis. On the other hand, the rapid recombination of photogenerated electron-hole pairs on TiO₂ particles leads to a low concentration of electrons or holes is another vital limiting factor to the efficiency of photocatalysis. Such, we employ a novel strategy to fabricate TiO₂ nanocomposites to enhance electron-hole separation and improve the response of TiO₂ to visible light.The electrospinning technique coupled with solvothermal process has been employed to successfully synthesized TiO₂/Ag heteroarchitectures. In the case of solvothermal processing, DMF （dimethylformamide） is selected as the solvent and reducing agent, and the growth of Ag nanostructures grown on TiO₂ nanofibers are controlled via tuning reaction time. The photocatalytic activity of the TiO₂/Ag heteroarchictures are compared with that of the pure TiO₂ nanofibers for degradating rhodamine B （RB） under visible light illumination. The photocatalytic mechanism of the TiO₂/Ag nanocomposite fibers is also discussed. The photocatalyst of TiO₂/CdS nanocomposites incorporating has been by prepared electrospinning technique and hydrothermal method. Here, cysteine is served as the sulfur donor as well as chelating reagent in hydrothermal synthesis of TiO₂/CdS nanocomposite fibers. In addition, we can alter both the size and coverage of CdS nanoparticles on TiO₂ nanofibers only by tuning reactant concentrations. Here, CdS nanoparticles acting as an effective and stable sensitizer for the TiO₂ nanofibers. The photocatalytic activity of TiO₂/CdS heteroarchictures are compared with that of the pure TiO₂ nanofibers for degradating rhodamine B （RB） under visible light illumination. It was worth noting that the cooperative photocatalytic mechanism of the TiO₂/CdS heteroarchitectures is also raised.A facile and straightforward route has been employed to synthesize TiO₂/PbS heteroarchitectures with secondary PbS nanostructures well dispersed on primary TiO₂ nanofibers substrates. It is worth noting that the shape of the PbS nanocrystals can be varied from nanocubes to nanoparticles with corresponding to deionized water and acetylacetone served as solvent, respectively. Particularly, the formation of as-prepared TiO₂/PbS heteroarchitectures is proposed. Due to larger surface-to-volume ratio and higher photon-to-exciton conversion efficiency, possibly, TiO₂/PbS heteroarchical nanocomposites would display potential applications in photochemical solar cells and other optoelectronic devices as well as photocatalytic domain presently.