卟啉可控自组装构筑高效可见光光解水光敏剂

Water splitting by visible light is critically needed for the sustainability of our society since fossil fuels cause serious environmental problems. In this program, we developed two simple processes, called acid base neutralization/micelle confined and microemulsion assisted/mesoscale transformation self-assembly processes. Through confined noncovalent interactions of porphyrin within surfactant micelles, nanocrystals with a series of morphologies will be synthesized with controlled size and dimension. The ability to control size and shape provides enhanced properties due to size- and shape dependent effects and collective behavior from self-assembled vicinity building blocks. The long range π-π stacking will solve the problems of short excited state electron-hole lifetime, low visible light utilization, indispensable in water and poor stability. Also, the nanostructure will short the distance to active site and enhance the photocatalytic hydrogen evolution efficiency. The catalytic activity for water-spliting will be investigated under visible light irradiation. Finally, the relationship between porphyrin nanocrystals and hydrogen evolution efficiency will be thoroughly investigated in order to get a series of photosensitizers with high performance.

可见光光解水制氢是解决能源和环境问题的有效途径，关键在于新型光敏剂材料的制备及改性。目前常见的卟啉基光敏剂普遍存在可见光利用率低、激发态电子-空穴对寿命短、不易水相分散以及稳定性较差的问题。本项目拟采用酸碱中和-胶束限域以及微乳辅助-介相转移两种卟啉可控自组装方法，设计和控制分子间弱键相互作用，制备组成、形貌、结构可控的水相单分散卟啉组装体，利用其长程有序的π-π堆积，可以有效的增强组装体的可见光吸收截面积，增强分子间激发态能量和电子转移的效率，降低电子-空穴的复合，提高激发态电子-空穴寿命，提高光敏剂的稳定性、获得高效可见光光敏剂。在此基础上深入研究卟啉种类、官能团、分子堆积方式与产氢性能间的关系，为开发新型高效可见光光敏剂提供了新的途径及理论探索。

可见光光解水制氢是解决能源和环境问题的有效途径，关键在于新型光敏剂材料的制备及改性。目前常见的卟啉基光敏剂普遍存在可见光利用率低、激发态电子-空穴对寿命短、不易水相分散以及稳定性较差的问题。本项目采用酸碱中和-胶束限域以及微乳辅助-介相转移两种卟啉可控自组装方法，通过设计和控制分子间弱键相互作用，制备了一系列组成、形貌、结构可控的水相单分散卟啉组装体，利用其长程有序的π-π堆积，有效的增强组装体的可见光吸收截面积，增强分子间激发态能量和电子转移的效率，降低电子-空穴的复合，提高激发态电子-空穴寿命，提高光敏剂的稳定性、获得高效可见光光敏剂。通过共催化剂的光沉积和开尔文探针力显微镜(KPFM)的测量表明，光生电子和空穴在不同的活性位点上有选择性的聚集。结合理论计算，我们发现有序堆积改变了分子的对称性，诱导了分子偶极子，并沿π-π堆叠方向线性增加，形成了一个强的内置电场。内置的电场驱动光生电子和空穴，从而沿着不同的方向进行独特的交叉传输。这些发现揭示了有序的堆叠结构如何促进光催化，并为高效的水分裂提供了一种新的方法。