Fabrication And Characterization Of Electrospun Samarium-Doped Titanium Dioxide/Carbon Nanofiber Photocatalyst

Titanium dioxide (TiO2) has attracted a great deal of attention in organic pollutants treatment because of its large specific surface area, stable chemical properties, nontoxicity and excellent photocatalytic activity. However, there are two problems in the application of TiO2 photocatalyst:First, the photocatalytic efficiency of pure nano-TiO2 powder is quite finite. Second, the nanoparticles are easy reuniting and flowing away in liquid solution, and also difficult to reclaim. These two factors inhibit the industrial application of nano-TiO2 photocatalyst significantly. Many researches have proved that doping modification and immobilization of TiO2 onto the supports with large surface areas are two effective means to solve the problems above.Electrospinning is a simple and effective technique for preparation of organic/inorganic hybrid nanofibres with large surface areas. In this paper, Sm-doped titanium oxoacetate/polyacrylonitrile [Sm-TiO(OAc)2/PAN] nanofibers were fabricated by electrospinning method. The Sm-doped TiO2/carbon nanofibers (Sm-TiO2/CNFs) photocatalyst was obtained through the subsequent heat stretching and preoxidation, ammonia treatment, and calcination of electrospun Sm-TiO(OAc)2/PAN nanofibers. Variations in morphology, crystal structure, and chemical composition of nanofibers were characterized with TEM, FESEM, XRD, FT-IR, EDX and XPS, respectively. The photocatalytic activity of Sm-TiO2/CNFs was characterized by photocatalytic degradation of methyl orange (MO) in aqueous solution under the UV irradiation. The results show that the surface of electrospun Sm-TiO (OAc)2/PAN nanofibers is rough and the nanofiber diameter is about 700nm. After 250℃heat stretching and preoxidation, the nanofibers possess highly orientation and become smoother, the average diameter of nanofibers decreases to 500-600nm due to physical and chemical shrinkage. After ammonia treatment and 600℃calcination, the average diameter of preoxidized nanofibers drop further to 250-350nm, and the surfaces of CNFs are interspersed with about 25wt% of anatase Sm-TiO2 nanoparticles, of which the average grain size is about 10nm. The photocatalytic activity of Sm-TiO2/CNFs is higher than that of TiO2/CNFs under the same UV irradiation conditions because doping Sm3+ may inhibit the recombination of electron-hole pair and increase the content of adsorbed oxygen, resulting in the generatinon of more powerful oxidizing free radical to degrade methyl orange.