凹凸棒石/氮化碳/聚苯胺多级结构材料的构筑及光催化燃油深度脱硫作用

Sulphur oxide emitted from the combustion of fuel oil is one of the major contributions to acid rain and atmospheric haze. Therefore, it is of great importance to design green photocatalyst utilizing inexpensive clay mineral materials for deeply removing sulphur-containing organics from liquid fuels. In this project, g-C3N4 nanosheets will be proposed to grow on the surface of attapulgite-skeleton by an “in-situ polymerization-pyrolysis” approach. Then polyaniline will be further assembled on the surface of g-C3N4 to generate heterostructure with energy band match. Thus, attapulgite/g-C3N4/polyaniline ternary functional composites with dendrimer-like hierarchical structure are constructed. The obtained composites have excellent adsorptive and efficient catalytic capacity for sulphur-containing organics. The growth mechanism and the micro-structure evolution of g-C3N4 will be investigated. The band gap state of g-C3N4/polyaniline heterojunction, as well as the mechanism of transfer and recombination of photo-generated carrier, will be illustrated. The coupling-adsorption behavior between polyaniline and organosulfur under the molecular level will also be illuminated. The interaction effect derived from ternary ingredients and the synergistic mechanism for catalytic desulfurization will be revealed. This project is believed to provide theoretical basis for the construction of low-cost and efficient photocatalytic materials for deep desulfurization.

燃油燃烧排放的硫氧化物是造成酸雨和雾霾的重要因素之一，利用廉价纳米粘土矿物材料设计绿色光催化剂以深度脱除油品中含硫有机化合物具有重要的科学意义。本项目以凹凸棒石晶体为骨架，采用“原位聚合-热解”法在凹凸棒石表面定向生长氮化碳纳米片，进而在氮化碳表面组装禁带宽度可调的聚苯胺形成与之能级匹配的异质结，构筑一种枝叶状多级结构的凹凸棒石/氮化碳/聚苯胺三元功能材料，该材料对汽油中的含硫有机物兼具优异吸附与高效光催化功能。探究氮化碳生长机制和微观结构的演化过程；阐明氮化碳/聚苯胺异质结的带隙状态的调控规律和光生载流子转移与复合机制，从分子层面上阐述聚苯胺与含硫有机化合物的耦合吸附行为；揭示凹凸棒石、氮化碳、聚苯胺三元组分的交互效应及协同催化脱硫机理，为构建一种低廉、高效深度脱硫光催化材料奠定理论基础。

石墨相氮化碳（g-C3N4）是一种新型可见光响应的非金属基光催化材料，具有简便的制备工艺、优异的热和化学稳定性等优点而被广泛用于光催化领域。然而，g-C3N4 材料往往呈现片层结构，存在诸多缺点。为此，项目主要以一维纳米结构的凹凸棒石为骨架，通过构建凹凸棒石/g-C3N4复合物来解决片层g-C3N4所存在的缺陷。以凹凸棒石/g-C3N4为复合载体进一步负载半导体，构筑多种具有多级结构的凹凸棒石基光催化剂，评价其光催化性能。主要研究内容与结果如下：.1. 为了获得一维纳米g-C3N4，项目先采用水热法在凹凸棒石棒晶表面生成g-C3N4前驱体薄膜，然后采用溶胶-凝胶法在g-C3N4前驱体表面进一步复合LaCoO3前驱体，最后通过一步高温煅烧法制备g-C3N4/LaCoO3异质结，即获得Z-型异质结构的凹凸棒石/g-C3N4/LaCoO3光催化剂。此方法有效解决了g-C3N4在凹凸棒石棒晶表面的成膜性能和LaCoO3纳米粒子均匀牢固负载难题，从而有效提高了该光催化材料的可见光响应、吸收能力和光生电子-空穴对的分离效率。.2. 光催化剂TiO2依赖于紫外光驱动，项目以g-C3N4量子点（CNQD）对纳米TiO2进行修饰，同时对一维纳米凹凸棒石进行导电功能化改性。以导电凹凸棒石为核体，利用导电层中Sb-SnO2导电颗粒作为晶种诱导剂，通过水热法在导电凹凸棒石表面原位生长TiO2纳米棒阵列制得多级结构的TiO2/导电凹凸棒石复合材料，然后通过浸渍法进一步复合CNQD，成功制备出多级结构的CNQD-TiO2/导电凹凸棒石光催化剂，从而拓宽了其可见光响应范围，增强了其对可见光的吸收和电子传输性能。.3. 三维互穿网络多级孔结构材料在光催化领域备受关注。本项目利用凹凸棒石的一维纳米结构特性和胶体特性，以一维凹凸棒石为硬模板，氨基三亚甲基膦酸为交联剂，聚苯胺为碳源，制备了凹凸棒石/聚苯胺复合凝胶，最后通过高温热解和去模板等工艺成功构建了氮掺杂多级孔结构的三维交联碳纳米管，可广泛用作光催化材料。