离子液体辅助高光催化活性窄带隙空心自组装体的可控构筑

Narrow band gap semiconductors can directly absorb the visible light from solar energy and remove the organic pollutants as photocatalyst. Therefore, the development of the new narrow band gap semiconductors with high photocatalytic activity, provides the ideal way to solve the problems of energy shortage and environment pollution. Nanometer semiconductors have high activity, low stability and are difficult to be separated and recovered. Hollow structures have the advantages of low density, high specific surface area and many catalytic centers. Utilizing the special structures of self-assembly, this project plans to study the controllable synthesis of narrow band gap hollow self-assembles with high catalytic activities. As the green and designable solvents, ionic liquids have the incomparable advantages of the conventional solvents in the synthesis of materials. By adjusting of the combination of cation-anion ions and the side chain groups, a simple, effective and repeatable route is established to fabricate narrow band gap hollow self-assemblies. Through this research, we are going to find out the key factors affecting the hollow structures, make clear the interactions between ionic liquids and nanoparticles, elucidate the formation mechanism of hollow self-assembles, clarify the internal relations of morphology and structure with visible light photocatalytic activity, cycling stablility and catalyst regeneration, and sum up the law. Finally, it is expected to draw the conclusions of the scientific value and lay the theoretical and practical foundations for the controllable design of visible light photocatalysts with high activities and searching for the new materials, which has the important academic significance and application value.

窄带隙半导体材料能直接吸收太阳能中的可见光，催化降解有机污染物，因而开发新型高活性窄带隙光催化剂，是解决能源短缺和环境污染问题的理想途径。基于纳米半导体材料具有活性高、稳定性差、分离回收难的特点，发挥空心结构密度小、比表面积大、催化中心多的优势，利用自组装体的特殊结构，本项目拟探索高活性窄带隙空心自组装体的合成研究。离子液体作为一种绿色、可设计型溶剂，在材料合成中具有传统溶剂无法比拟的优势。利用离子液体中阴阳离子组合和侧链基团可调，实现窄带隙空心自组装体的可控构筑，建立简单、有效、可重复的合成路线；找出影响空心结构的关键因素，明确离子液体与纳米单体之间的相互作用，揭示形成机理；阐明材料的形貌和结构与可见光催化活性、循环稳定性和催化剂再生等之间的内在联系，总结规律，得出有科学价值的结论，为实现高活性可见光催化材料的可控设计和寻找新型结构提供了理论依据和实践基础，具有重要的学术意义和应用价值。

开发可见光响应型半导体光催化剂是光催化技术实用化的关键，窄带隙半导体空心自组装体具有纳米材料活性高、比表面积大、稳定性好、不易团聚等优点，能直接吸收太阳能中的可见光，催化降解有机污染物，因而开发新型高活性窄带隙空心自组装体，是缓解能源短缺和环境污染问题的理想途径。本项目基于离子液体在材料合成中具有传统溶剂无法比拟的优势，采用溶剂热法、溶液法、热处理等，构筑了各种窄带隙半导体可见光催化剂，如纳米立方块构筑的Cu2O空心纳米球、纳米丝构筑的CuO空心微球、纳米粒子构筑的ZnO空心微球、纳米片构筑的ZnO空心纳米球、纳米片构筑的α-Fe2O3空心纳米球、纳米片构筑的BiOX（X=Cl、Br、I）自组装体。使用SEM、TEM、HRTEM、XRD、XPS、BET、UV-vis DRS等对半导体的形貌、结构、组成、比表面积、多孔性和禁带宽度进行表征，发现产物具有比表面积大、孔隙率高、禁带宽度窄等特点；研究了反应时间对产物形貌、结构和组成的影响，揭示了形成机理；调节反应温度、离子液体的种类和浓度、溶液pH值等，合成了不同形貌结构的光催化剂。研究窄带隙自组装体对烷基酚类、甲基橙、活性红等污染物的光催化性能，发现催化剂均表现出良好的光催化活性和循环稳定性；高的表观速率常数、高的暂态光电电流密度和低的荧光强度，表明窄带隙自组装体对可见光吸收能力强，光生电子空穴分离效率高，探讨了光催化反应机理。基于复合半导体在提高光催化性能方面表现出的优越性，合成了纳米空心球构筑的CuO/ZnO微球、BiVO4/g-C3N4复合自组装体、纳米丝包裹的CuO/g-C3N4空心微球、纳米丝包裹的ZnO/g-C3N4空心微球和空心纳米球等窄带隙复合半导体光催化剂，发现催化剂具有优于单独半导体的光催化性能，并初步阐明了催化剂的形貌、结构、组成与性能之间的内在联系。本项目研究为新型高活性可见光催化剂的开发和利用提供了理论依据和实践基础，具有重要的学术意义和应用价值。已发表科研论文9篇，其中SCI检索论文7篇，已申请或授权国家发明专利7项，获得科研奖励1项。