Photocatalytic Reduction Of Cr（Ⅵ） By TiO₂-HPW Semiconductor Compound Nanofibers Prepared Via Electrospinning Technology

With the rapid development of the global economy the energy crisis and environmental pollution have become aglobal issue to be addressed urgently. Semiconductor materials gradually caused widespread concern due to their potential applications in environmental purification and solving the energy problem.Ti O2 is one of the most studied materials thanks to its chemical stability, nontoxic and efficient photosensitivity among a large number of semiconductor photocatalysts. Despite its great potential, Ti O2 is a wide band gap semiconductor only photoactivated under UV light irradiation(5% energy of the solar spectrum). The low photocatalytic efficiency of Ti O2 hinders the commercialization due to the high recombination ratio of photo-induced electrons(e-) and holes(h+) and lower solar energy utilization efficiency.Thus development of solar light active Ti O2 photocatalyst with high catalytic efficiency is always of great interest and demand in both academic and commercial sectors.Electrospinning is by far the most effective method to fabricate one-dimensional continuous nanofibers. Electrospun fibrous membranes have many advantages such as high porosity, large surface area, light weight, universality for a variety of materials, and so on.The main contents are as follows in the thesis:1.Ti O2 semiconductor nanofibers were synthesized via electrospinning and sol-gel method to obtain the best electrospinning condition.2. Ti O2 semiconductor nanofibers were prepared by sol-gel and electrospinning method and calcined at different temprature.The obtained samples were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD).3.Ti O2-HPW semiconductor nanocomposites which had different concentration ratio were prepared by sol-gel and electrospinning method.The obtained samples were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and so on.4.The resulting samples which had the same mass were used to degradate K2Cr2O7 in aqueous solution to evaluate the best calcined condition of Ti O2 and to evaluate the best concentration ratio and the best calcined condition of Ti O2-HPW. We got the degradation theory of Ti O2-HPW after characterized by XPS and so on. The results show that Ti O2 which were calcinned at 450℃ for 2h have the best performence when they are used to degradate K2Cr2O7 in aqueous solution; Ti O2-HPW which were calcinned at 550 ℃ for 5h have the best performence when they are used to degradate K2Cr2O7 in aqueous solution, while the W/(W+Ti)of Ti O2-HPW is 20%; Ti O2-HPW has much better degradation performence than Ti O2.