基于孔道有序AAO模板的三维LDHs薄膜的制备及其光催化性能调控研究

Layered double hydroxides（LDHs）have been applied as efficient photocatalysts in recent years, which possess a layered structure consisting of positively charged octahedral layers of mixed metal hydroxides with interlayer galleries occupied by anions. In this project, three-dimensional LDHs films would be fabricated on highly ordered porous anodic aluminum oxide (AAO) templates using a in-situ growth method. The formation mechanism and the influence of preparation conditions on the morphology and the microstructure of LDHs films will be studied. The adjustments on microstructure, type/proportion of metal ions of LDHs films and semiconductor composite LDHs/AAO films would be used to modify the light absorption characteristics and improve the performance of photocatalytic degradation of organic pollutants on LDHs films. The results obtained could be used to discover the methods and mechanisms to improve the photocatalytic efficiency of the LDHs films. In addition, this work should lay a foundation not only in the application of LDHs film materials in the control of environmental pollutants but also in various potential applications.

层状双金属氢氧化物（LDHs）具有层板金属阳离子多变性和结构的可调控性，已在光催化领域中崭露头角。本项目以孔道有序且呈六方排列的多孔阳极氧化铝（AAO）模板为基底，采用原位化学生长法制备具有一定形貌和取向的三维LDHs/AAO薄膜，考察制备条件对薄膜形貌和微观结构的影响，揭示三维有序LDHs薄膜的生长机制；通过改变微观结构、LDHs层板中金属离子的种类和比例以及半导体复合等方法调控LDHs/AAO薄膜的吸收光特性和光催化降解有机污染物性能，探索该类催化剂光催化降解有机污染物能力调控的规律和机理，为新型有序LDHs薄膜材料的制备以及在光催化领域的应用奠定基础，并提供新的发展思路。

以提高材料的工作效率为目的，根据其应用要求设计并制备材料一直是研究者关注的研究热点。本项目选择在催化、分离、吸附等领域应用广泛的层状双金属氢氧化物（LDHs）为研究对象，以多孔阳极氧化铝模板（AAO）为基底，采用无沉淀剂的原位化学生长法，首次成功制备出三维ZnAl-LDHs/AAO和NiAl-LDHs/AAO薄膜，并对薄膜的生长机理进行了详细的实验研究，发现制备液的pH值、金属离子浓度及反应时间是影响其形成的关键因素，该薄膜在光催化降解有机污染物的实验中表现出超越二维薄膜的优异光催化活性。在三维LDHs/AAO薄膜基础上，进一步考察了M(II)（Co2+、Cu2+、Cd2+）和M(III)（Cr3+、Fe3+、Al3+）等金属离子对于M(M=Ni, Zn)Al-LDHs/AAO薄膜的形貌、结构和光催化活性等的影响。结果发现，在所研究的M(II)或M(III)离子共存下，三维LDHs/AAO薄膜是否形成与其光催化活性密切相关，Co2+、Cd2+、Cr3+等金属离子在反应液中共存时，虽然会不同程度的影响LDHs/AAO的形貌，但其光催化活性均得到提高；Cu2+、Fe3+等金属离子在反应液中共存时，会抑制LDHs的形成，进而造成薄膜光催化活性的大幅下降；而反应液中外加Al3+离子时，ZnAl-LDHs因无法形成而活性大为下降，NiAl-LDHs却更易形成且结晶度提高。对于金属氢氧化物/氧化物复合的LDHs/AAO薄膜进行了初步探索，结果发现铟氢氧化物复合的NiAAO薄膜表现出很好的光催化性能。本项目研究思路和研究结果可为多相催化、吸附、分离等领域的材料的设计和制备提供重要参考。