金属酞菁(MPc)/电纺碳纳米纤维(CNFs)异质结材料的构筑及可见光催化性质研究

Waste water problems are becoming more and more serious. Photocatalysis, as a "green" technique, offers great potential for complete elimination of toxic chemicals in the waste-water treatment through its efficiency and broad applicability. Among all kinds of photocatalyst，metal phthalocyanines might use sunlight as the energy source to degrade organic pollutions and widely used for waste-water treatment because of the intense absorption bands in the longer wavelength region of the visible light in a solar spectra. However, metal phthalocyanines suffer from considerable recombination of the photogenerated electron-hole pairs for low quantum yield and the difficulty in separating the nanostructural photocatalysts for large-scale applications. In this item, we plan to fabricate MPc/CNFs heterostructures. The one-dimensional CNFs have been widely used as ideal electron pathways owing to their good conductivity, which make it possible that electrons leaving from a depleted region based on the fact the CNFs have a higher work function than MPc into the CNFs could be captured and transported through highly conductive long CNFs. The synergistic effect between CNFs and MPc might lead to the high catalytic efficiency. Meanwhile, the MPc/CNFs nanofiber heterostructures could be reclaimed easily by sedimentation without a decrease of the photocatalytic activity due to the large length to diameter ratio of CNFs and the one-dimensional nanostructural property.

污水问题日益严重，光催化作用因其对污染物降解彻底、有效而被认为是处理污水问题的绿色途径。在各类光催化材料中，金属酞菁光催化剂在可见光区域有强烈的吸收，能利用太阳光有效降解各种有机污染物，从而解决了传统光催化剂对太阳能利用率低的难题，被广泛应用于污水处理方面。尽管如此，金属酞菁光催化剂在实际使用过程中的量子化产率和回收再利用率仍有待提高。本项目拟将金属酞菁(MPc)与一维电纺碳纳米纤维(CNFs)复合，构建MPc/CNFs异质结光催化材料。利用一维电纺碳纳米纤维高导电性能，易于捕获传输光生电子特性抑制酞菁光生电子和空穴的复合，从而提高光催化效率。同时，利用CNFs的长径比，错综交织成的纳米网毡结构易于自沉降的性能解决光催化材料的回收再利用难的问题。

可见光光催化剂对污水处理应用中，提高其光量子产率以及循环利用率是目前的研究热点，本项目主要研究内容是围绕在可见光区域有强烈吸收的金属酞菁(MPc)与一维电纺碳纳米纤维(CNFs)复合，构建MPc/CNFs异质结光催化材料，利用CNFs的高导电性减少MPc光生电子和空穴的复合几率，同时，利用CNFs的长径比，错综交织成的纳米网毡结构易于自沉降的性能解决光催化材料的回收再利用难的问题。通过研究发现，溶剂热制备的金属铁酞菁在可见光照下5h对罗丹明B的降解率达到90%，远高于P25，且形貌易于控制。而将铁酞菁与电纺CNFs复合后，经3h的可见光照后，光催化剂对罗丹明B的降解率达到91%以上，且复合催化剂材料易于回收再利用，经过三次循环使用，催化剂的催化效率无明显降低，光电流响应测试显示TNFePc/CNFs异质结的电流密度有明显的增强，约为纯铁酞菁的1.8倍，说明，与CNFs复合后，实现了光生电子和空穴的有效分离，提高了金属酞菁的光催化效率。通过 改变溶剂热反应条件可以调控铁酞菁在CNFs上的覆盖密度，且不同覆盖密度下的TNFePc/CNFs异质结材料在可见光照下，可实现对甲基橙的有效降解。本研究为提高光催化剂的催化效率，降低催化剂的循环再利用成本提供了实验基础和理论指导。