新型三维有序大孔M@TiO2(M=CdS,Fe2O3,WO3)复合材料的可控制备及其光催化活性增强机制研究

This proposal is motivated by the in-depth treatment of the low concentration and refractory toxic pollutants in the petroleum refinery effluents(PRE). Based on the solar-light-driven photocatalytic technique, the main focus of the proposed research is the study and preparation of a series of visible light-responsive M@TiO2 (M=CdS, Fe2O3, WO3) composite semiconductor materials with three-dimensionally-ordered macroporous (3DOM) and hollow structures. The presence of 3DOM and hollow structures are benefited for the high adsorption and capture of macromolecules organic pollutants. Meanwhile, the formation of heterojunctions through coupling two different energy band gap semiconductors can constitute a directional charge channel, leading to the increase of electron-hole pair separation efficiency and the enhancement of the quantum yield of photocatalyst. The as-prepared samples would be characterized using various analysis technologies to investigate their surface physical-chemistry and optical physical-chemistry properties. According to the characterization results, the novel and efficient method of preparing the M@TiO2 composite nanomaterials will be developed, and the diffusion and capture process of toxic pollutants in the multi-dimensional porous structure, as well as the mechanism for the transfer of photogenerated charge carriers will be investigated. The relationships between micro-architectures and the catalytic performance of M@TiO2 composite materilas for photocatalytic degradation of PRE will also be studied, and this could help to achieve the advanced tunable functions for the synthesis of composite nanomaterials. Furthermore, this proposal will not only provide a new and significant approache to treat the PRE organic wastewater, but also promote the amalgamation of chemistry, materials, energy sources and environmental　subject, which have an important academic significance and application value.

针对含油废水中浓度低、有毒、难降解有机污染物深度去除的难题，本项目拟创新设计与合成具有三维有序大孔(3DOM)结构和空心结构的M@TiO2(M=CdS, Fe2O3, WO3)复合纳米光催化材料，利用3DOM结构和空心结构丰富的功能特性实现有毒大分子污染物的高效吸附和捕获；利用两种不同带隙宽度半导体耦合而形成的异质结构，构成定向电荷通道，实现光生电荷的高效分离，有效提高对可见光响应能力和光催化量子效率。利用各种光谱技术表征复合纳米材料的表面物理化学与光物理化学性能，探索针对典型水污染物治理的纳米材料新体系绿色制备和新合成方法，研究有毒污染物在多维孔道中的扩散和捕获过程以及光生载流子的界面迁移转换规律，揭示催化剂微观构型与催化性能之间的关系，实现纳米材料功能设计可调。本项目不仅为高效处理难降解污染物提供一条崭新的途径，同时对促进化学、材料、环境等学科的交叉融合，具有重要的学术意义和应用价值。

太阳能光催化技术作为一种新型、绿色处理有机污染物的方法，具有能耗低、高效、无二次污染的鲜明特点。其研究关键是创制新型高效的纳米光催化剂材料。鉴于此，本项目设计与合成了一系列具有独特微观结构的复合纳米光催化材料，研究了所制备的系列光催化剂晶型组成、特殊形貌、孔道结构对降解大分子有毒污染物活性的影响规律，探索了有毒污染物在多维孔道中的扩散和捕获过程以及光生载流子的界面迁移转换规律，揭示了催化剂微观构型与催化性能之间的关系及光催化活性增强机制。.首先，本项目以SiO2微球为模板，分别辅以水热、溶胶凝胶、浸渍等方法制备了TiO2/CdS空心微球、SiO2/g-C3N4核壳微球、TiO2/rGO/SnS2空心微球和球中球g-C3N4@SiO2等复合光催化剂。此外，还以葡萄糖为模板合成了介孔Fe2O3/TiO2微球。与单一的半导体纳米颗粒材料相比，这些独特微球结构光催化剂的可见光活性和稳定性均得到大幅度提高，且易回收。这主要是由于①微球结构有利于光子的吸收和污染物分子的吸附和捕获。②微球结构的大比表面积提供了大量反应活性位点。③形成的异质结促进了光生电子空穴对的迁移与分离。.其次，本项目分别以PMMA阵列和介孔SiO2微球阵列为模板，采用胶晶模板法制备得到了3DOM N-TiO2, 3DOM Fe3+-TiO2, 3DOM SnS2@TiO2和3DOM g-C3N4等三维有序大孔结构复合光催化剂。这些具有3DOM结构的复合光催化材料不仅具有高的可见光降解活性，还具有优异的还原重金属离子及产氢活性。其活性增强的原因主要为①3DOM结构提供大量的界面化学反应活性位点，有利于反应物的吸附和捕获。②3DOM结构产生的多重散射和慢光子效应，提供了大量光吸收活性位点。③掺杂和形成的异质结可实现光生电荷的高效分离。.最后，本项目进一步拓展了催化剂的制备范围，制备了F-N共掺杂TiO2纳米光催化剂，BiOBr/TiO2纳米管和Ag-AgBr/TiO2纳米管异质结光催化剂。这些新型催化新材料均表现出了极高的可见光降解活性。.本项目研究成果不仅为合成具有3DOM结构和空心微球结构复合光催化剂提供了普适性的制备方法，还丰富人们对其光催化活性增强机制的理论认知，同时为该类光催化材料的实际应用提供了实践基础。