N-取代聚苯胺电纺丝纳米纤维负载可控量子点可见光下持续降解气态有机污染物

Recently, photocatalysts have attracted extensive attention because volatile organic compounds (VOCs) are identified as highly toxic or carcinogenic in nature and may cause both short- and long-term impacts on human health as well as on the natural ecosystem. Then, it is very important to seek and design a highly efficient photocatalyst to quickly and efficiently govern these pollutants. The zirconium metal organic framework (UIO-66) with different porous configuration and uniform distribution is prepared by changing the pressure in a supercritical system. The CdS quantum dots with a high ordering and size-contralled can be fabricated by controlling the growth of the quantum dots due to high specific surface area and confined spaces for MOFs. The relationship of the distribution of the pore size, specific surface area and the distribution of CdS quantum dots and the adsorption and degradation of the CdSQD/MOFs composite photocatalyst were studied by investigating the characteristics of the adsorption and degradation of VOCs. A formation mechanism of efficient photocatalyst will be constructed by the combination of adsorption and photocatalysis efficiency. The effective distribution and uniform dispersion of the photocatalyst is favorable to improve the adsorption effect of MOFs and the response to the target VOCs by polyaniline nanofiber loading photocatalysts using electrostatic spinning due to the hydrophobicity and functionality of polyaniline. This result will lead to a stable and reproducible catalytic system. To achieve the efficient degradation of volatile organic compounds under visible light irradiation, some influence factors including concentration, humidity and temperature will be further investigated to apply in practical condition.

光催化降解对于控制空气中挥发性有机化合物（VOCs）具有非常重要的作用。本项目采用超临界体系，通过控制压力来制备具有不同孔径大小的UIO-66（MOFs），再以多孔性MOFs为模板，在有限的空腔内限制生长制备均匀分散、排列有序的CdS量子点；通过探索复合催化剂对VOCs的吸附-降解的特点，研究MOFs的孔径分布、比表面积、CdS量子点的分布和分散与吸附-降解之间的构效关系，建立高效吸附和降解CdSQD/UIO-66复合催化剂的形成机制；通过研究静电纺丝制备聚苯胺纳米纤维负载催化剂的条件，实现催化剂在纤维中有效分布和均匀分散，达到改善潮湿条件下水分子对MOFs吸附影响和提高对目标VOCs的响应；通过探索催化系统对VOCs吸附和降解的影响因素，研究催化系统对VOCs的吸附与降解规律，控制吸附过程和光催化降解过程的协同关键因素，实现催化系统对空气中气态有机物在可见光下高效吸附和降解。

近年来，随着工业的发展，给人们的生活水平带来了极大的提高，但由于盲目和短视的发展，也给环境造成了一定的破坏，使得环境污染日趋严重。因而，有效控制和治理各种化学污染是环境综合治理的重点，研究化学污染物无害化的方法是环境保护的关键。为了能有效地降解环境中的污染物，发展反应性吸附过程已成为改善空气质量尤其是高效除去污染物的重要手段。利用多孔吸附材料发达的孔隙结构和巨大比表面积，再依靠多孔材料表面存在的未平衡的分子引力或化学键力可对低浓度有效地吸附净化。该项目首先采用静电纺丝的方法，将PAN，乙酸镉以及N-苯基甘氨酸进行纺丝，再通过原位聚合和引入硫源，通过引入导电性高，比表面积大的还原氧化石墨烯，制备成CdS@NPANI-rGO-PAN复合材料，其比表面积为19.43 m2/g，能带间隙为2.20 eV，光电流大小为1.4 μA/cm2。并且在第一次循环中降解了81.3%的RhB染料，经过1000 min五次循环后仍可保持 79.4%。导电材料的加入有效地降低了光生电子和空穴的重新复合，增强了复合材料的光降解能力。再就是为了克服纳米级粒子容易团聚，以防止光生电子的下降，因此，项目选用一种稳定的多孔材料MOF，通过与纳米CdS形成异质结结构。结果发现，拥有更大比表面积的催化剂体系其光电流最大，可达到1.53 µA/cm2。经历5次循环催化后催化效率仍能保持在92.87%。再就是采用层层组装的方式在CdSNPs表面自组装形成UIO-66-NH2壳层，形成核-壳纳米结构。研究发现，控制自组装的循环次数可以改变复合物的壳层厚度，结果表明，自组装循环5次时光电流最大，可达到1.35 µA/cm2，并且经历4次循环催化后仍可保持94.01%的降解效率。项目通过制备一种反应吸附性的光催化材料，能有效地提高催化剂对污染物的降解，而且也增强了催化剂的稳定，进而提高了催化效率。