Study On Preparation And Photocatalysis Activity Of Modified TiO₂Nanomaterials By Electrospinning

In recent years, a large number of industrial wastewater containing organic syntheticdyes has been producted with the development of technoloty. In order to solve theseproblems, many researchers adopted a series of physical and chemical methods to treat thewastewater, but had little effect. Semiconductor photocatalysis is an advanced technologythat employed the electrons on conduction band and holes on valence band by absorbingthe photons. Pollutants can be removed via oxidization or reduction and hydrogen can beobtained via water-splitting. TiO2has been widely studied because of its chemical stability,safe, non-polluting, low cost. However, its wide band gap reduced the utilization of solarenergy. Therefore, how to improve the sunlight absorption rate of TiO2, enhanced itsphotocatalytic activity under visible light, had become a hot research of fieldphotocatalysis. For this, the paper devoted to fabricate a semiconductor composite bymodifing TiO2nanofibers. A novel heterogeneous photocatalytic composite was obtainedby compositing ZnxCd1-xS solid solution and TiO2nanofiber via sol-gel process,electrospinning technique, hydrothermal method or their recombination. For this purpose,the photocatalytic activities of the composite were investigated. Specific research contentsare as follows:(1) TiO2nanofiber prepared by electrospinning as matrix, heterostructured ZnxCd1-xS/TiO2composite photocatalyst were prepared via hydrothermal growth, initially investigated thephotocatalysis mechanism and growth mechanism of composite photocatalyst. The resultsshowed that the composite of ZnxCd1-xS solid solution and TiO2nanofiber can effectivelyimprove the visible light spectrum response of TiO2nanofiber and its photocatalyticactivity. Hydrothermal temperature and hydrothermal time were optimized further, andfound that the two factors have obviously impact on photocatalytic activity. Whenhydrothermal temperature was200℃, the hydrothermal time was24hour, thephotocatalytic activity of photocatalyst reached the best, respectively. Meantime, it wasfound that the loading amount of ZnxCd1-xS solid solution and Zn/Cd played importantroles in the photocatalytic activity of ZnxCd1-xS/TiO2composite photocatalyst.(2) The ZnxCd1-xS/TiO2nanofibers were successfully synthesized by the combination ofelectrospinning technique and hydrothermal method. This nanofibers characterized for thestructural, optical, and morphological properties by XRD, SEM, UV-vis DRS, EDS analysis. By adjusting the x value, the photocatalytic performance of photocatalysts wasexamined and found that ZnxCd1-xS/TiO2composite photocatalyst had the bestphotocatalytic activity when x value reached0.6. Then, the paper studied the influence ofphotocatalytic activity via changing TiO2matrix crystal structure. The results showed thatTiO2nanometer fiber was the mixed crystals,and the photocatalytic performance ofZn0.6Cd0.4S/TiO2composite photocatalyst was the best, when the calcinations temperaturewas500℃.(3) Zn0.6Cd0.4S/TiO2composite photocatalysts were fabricated by hydrothermal methodusing TiO2nanofibers as reactant. The influence of photocatalyst performance ofZn0.6Cd0.4S/TiO2composite photocatalysts were studied by adjusting the loading amount ofZn0.6Cd0.4S solid solution and the concentration of S source. This nanofibers characterizedfor the structural, optical, and morphological properties by XRD, SEM, UV-vis DRSanalysis. The photocatalytic properties of the photocatalysts were studied via rhodamine Bdegradation as the model reaction. The result showed that when the loading amount ofZn0.6Cd0.4S solid solution(the molar ratio of TiO2) was1, the concentration of S source(themolar ratio of TiO2) was1, the photocatalyst degration effect of Zn0.6Cd0.4S/TiO2composite photocatalysts was the best. Meantime, it was found that the photocatalystperformance of Zn0.6Cd0.4S/TiO2composite photocatalytic was determined by the mutualinfluence of S/Ti, Zn/Cd and the band gap.