TiO2/卟啉/MOFs超薄异质体的层级构筑及光催化还原CO2研究

In order to enhance the visible light utilization and CO2 uptake rate of TiO2 for photocatalytic CO2 reduction, a novel TiO2/porphyrins/MOFs ultrathin heterogeneous composite was fabricated by introducing a transition layer of porphyrins. The functional groups of porphyrins can not only sensitize TiO2 core but also self-assemble into MOFs shell, which helps the hierarchical construction and functional integration of TiO2/porphyrins/MOFs ultrathin heterogeneous composite. The MOFs shell with high porosity, large surface area could promote the CO2 adsorption, the in-between porphyrins could efficiently absorb visible light and transfer the photogenerated electrons in the conduction band of the porphyrins to the conduction band of TiO2, and the inner TiO2 ultrathin nanosheet which accepted the electrons could efficiently reduce CO2 around. According to adjustment of the matching combination of porphyrins/MOFs, the functional groups and coordinated centre metal atom of the porphyrins, and the porosity, pore size, open the metal sites of the MOFs, we aim to enhance the integrated performance of the TiO2/porphyrins/MOFs ultrathin heterogeneous composite, and develop one kind of the catalysts with wide light absorption band, high CO2 uptake rate and superior catalytic properties, and finally promote their applications in photocatalytic CO2 reduction.

针对TiO2在光催化还原CO2反应中存在可见光利用率低，CO2吸附性能差等问题，本项目提出了TiO2/卟啉/MOFs超薄异质体的新概念，巧妙地在TiO2和MOFs之间设计了卟啉过渡层，利用卟啉外围官能团敏化修饰内层TiO2超薄纳米片内核和原位组装外层MOFs壳层，实现TiO2/卟啉/MOFs超薄异质体的层级构筑与功能集成：外层高孔隙率、大比表面积的MOFs层作为吸附区可有效吸附CO2分子，中间卟啉化合物作为光吸收区可有效吸收可见光并将光生电子从卟啉的导带向TiO2导带的传递，内层接收到卟啉激发电子的TiO2超薄纳米片作为催化区将富集在其表面的CO2进行高效转化。通过调控卟啉/MOFs的匹配组合，卟啉外围取代基和配位中心金属离子，MOFs孔隙率、孔径大小、开放金属位点等参数，优化TiO2/卟啉/MOFs超薄异质体的综合性能，并推动其在CO2光催化还原领域中的应用。

本项目针对TiO2在光催化还原CO2反应中存在可见光利用率低，CO2吸附性能差等问题，提出了TiO2/卟啉/MOFs复合体的新概念，通过原位生长、多级组装和结构调控等方法构筑了TiO2/TCPP，TiO2/TPP，TiO2/MTCPP（M=Fe，Zn，Co），TiO2/TCPP/UiO-66、镍掺杂NH2-MIL-125（Ti）、双配体NH2-MIL-125（Ti）等多种钛基光催化复合材料。掌握了TiO2/卟啉/MOFs超薄异质体构筑原则和调控规律，揭示了TiO2超薄纳米片、卟啉及MOFs的协同作用机制，卟啉的引入拓宽了复合材料的光谱响应范围，作为光吸收区可有效吸收可见光并将光生电子从卟啉的导带向二氧化钛导带的传递，进而实现优异的可见光光催化性能。所开发的TiO2NS/11.5% TCPP得到的CO生成速率可达141.74 µmol/gh，为未负载TCPP样品的CO生成速率的37倍。所取得的研究成果，目前在Nano Energy，Chemical Engineering Journal等国际期刊发表SCI论文22篇，其中第一标注论文6篇；申请国家发明专利5项。培养青年教师骨干2名，博士生2名，硕士生3名，项目执行期间项目负责人晋升为副教授；指导本科生创新项目2组。项目负责人赴美国 University of California, Los Angeles 卢云峰教授课题组进行了为期9个月的访学交流。