有序多孔铋系光催化剂的可控制备及其高效光催化性能研究

The surface areas and the photocatalytic reaction sites of bismuth based photocatalysts can be effectively increased by synthesis of porous structures with controllable pore size and order. The present reported soft template or hard template method is difficult to control the pore size and order simultaneously. Aiming at the subsistent problem, this project puts forward synthesizing porous bismuth based photocatalysts templated by amphiphilic block copolymer containing photosensitive cinnamic acid unit. This novel template combines the advances of soft template and hard template, and will be more likely to synthesis ordered porous bismuth based photocatalysts. First, the structures and sizes of amphiphilic block copolymer assembly will be adjusted by cinnamic acid unit position in the amphiphilic block copolymer, the ratio of soft/hard block in addition to the copolymer assembly method. And the assembly process of bismuth precursor at the interface of amphiphilic block copolymer will be studied. Then, the pore structure of the porous precursors will be further consolidated by photocrosslinking of photosensitive cinnamic acid unit under UV light irradiation, and the influence mechanism of photocrosslinking degree to pore structure will be discussed. Besides, the heating process in inert gas and in oxygen will be conducted in turn after the porous precursors obtained, through which the pore wall stability and the pore structure order will be increased by the in situ produced amorphous carbon as a rigid support. Therefore, this project provides an effective method to obtain porous bismuth based photocatalysts with adjustable pore sizes, ordered pore structures and high surface areas. The photocatalytic property of porous bismuth based photocatalysts under visible light irradiation will be evaluated by degradation of toxic and persistent organic pollutions, and the corresponding relationship between porous structure and high photocatalytic activity will be further revealed.

针对软模板法制备多孔铋系光催化剂在去除模板剂过程中的孔道坍塌以及硬模板法难以对孔径大小进行调控的问题，本项目拟设计合成光敏性肉桂酸基双亲嵌段共聚物为结构导向剂，使其兼具软、硬模板功能，制备孔径可调、孔道有序多孔铋系光催化材料。研究核心可描述为：调节光敏性肉桂酸基双亲嵌段共聚物中肉桂酸基位置、软/硬链段比以及聚合物组装方法，对模板剂组装体结构和尺寸进行控制；研究铋系前驱体以嵌段共聚物为模板的界面组装过程，利用模板剂中含光敏基团，在紫外光照下发生光交联，进一步增强模板剂对铋系前驱体的支撑作用；利用肉桂酸基链段含有大量sp2杂化碳原子可在惰性气氛中原位转化成无定形碳支撑体，有效防止模板剂去除后孔道坍塌，最终实现孔径可调、孔道有序的多孔铋系光催化剂的控制合成，并研究其形成机理。对有序多孔铋系光催化剂光催化性能进行研究，揭示多孔结构与高效光催化性能之间的构效关系，实现高效铋系光催化剂的构筑。

高效可见光响应光催化剂的研究一直是光催化领域的重要研究方向，也是实现光催化技术规模化应用的关键和核心问题。本项目结合纳米材料和多孔材料的制备方法，以构筑高效可见光响应光催化剂为最终研究目标，得到了一系列重要研究结果：利用自牺牲模板法制备了中空Bi2MoO6，具有大比表面积和表面孔洞机构，光催化性能优越。此外，利用含有sp2杂化碳原子的聚合物作为软硬模板设计和制备介孔C@TiO2@Ag光催化剂和介孔氮化碳，研究了反应条件、煅烧温度、比表面积等对光催化剂性能的影响规律，得到高效的多孔光催化剂；利用小分子辅助溶液制备超薄BiOBr和BiOClxBr1-x铋系光催化剂，探讨了晶面暴露比、暴露面积等对光催化性能的影响机制，指出活性晶面的暴露面积是影响二维纳米光催化材料性能的关键因素而非晶面暴露比；利用构筑异质结构，加快光生电子-空穴转移速率，设计高效铋系复合光催化剂如C3N4/BiVO4、Bi/BiOI、导电聚合物/BiPO4等，研究了组分比例对光催化性能的影响规律。因此，本课题从多角度深入研究，利用多孔结构、超薄结构、异质结构实现了高效铋系光催化材料的构筑，发表研究论文10篇，其中SCI论文6篇，申请国家发明专利4项，其中授权2项。同时为设计其他高效光催化材料提供了理论和实验依据，对促进光催化技术在环境污染物处理方面的大规模实际应用具有指导意义。