水相稳定宽光谱捕光金属-有机框架的制备及光解水制氢研究

Photocatalytic water splitting for hydrogen evolution by utilizing the solar energy is kind of a holy grail challenge in scientific filed. At present, photocatalytic decomposition of water to produce hydrogen still has challanges such as low visible light utilization, the photocorrosion of catalyst and low energy conversion efficiency. Therefore, designing and developing a high efficient water stability photocatalyst with a broad spectral response remains a challenging subject. On the basis of thermodynamics and dynamics, this project mainly focuses on the design and development of a wide-spectrum light-harvesting (with absorption edge of approximately 550 nm) metal-organic frameworks (MOFs) material with high water stability. It is intended to control the assembly of a catalytically active semiconductor metal oxygen cluster or molecular catalyst with an organic bridging ligand having visible light absorbing properties to construct some aqueous phase stability metal organic frameworks with wide spectrum response. The visible light utilization efficiency, migration and separation of photogenerated carriers are improved by structural adjustment or loading of cocatalyst, and also the "structural-effect relationship" between structure and hydrogen production performance is explored. Based on the above results , it is expected to improve the water stability and efficiency of solar hydrogen production of MOFs materials, expand new routes to design high-efficiency photocatalysts, and make certain contributions to the exploration and development of new catalysts.

利用太阳能进行分解水制氢是科学领域的“圣杯式”挑战课题，目前光催化分解水制氢仍然存在可见光利用率低、催化剂易发生光腐蚀和能量转化效率低等问题。因此，设计和开发宽光谱响应的高效稳定光解水催化剂依然是一个具有挑战性的课题。本项目从热力学和动力学出发围绕金属-有机框架（MOFs）的水稳定性和宽光谱吸收性能（带边约在550 nm），聚焦新型高效水相稳定的宽光谱捕光金属-有机框架光材料的设计和发展。拟选择具有可见光吸收性能的有机染料配体分别与高价态金属氧化物纳米簇或质子还原分子催化剂构筑水相稳定宽光谱捕光（吸收带边约在550 nm）金属-有机框架材料。通过调控有机桥连配体与金属簇节点或质子还原分子催化剂在热力学和动力学上的匹配获得MOFs光生载流子的有效迁移和分离，探索结构与制氢性能之间的“构效关系”，拓展新型高效太阳能分解水制氢催化剂的设计思路，为新型催化剂的探索和开发做出一定的贡献。

利用太阳能光催化分解水制氢，不但能够实现太阳能向绿氢的转化，而且可以减少碳排放，其中宽光谱响应的高效稳定光解水催化剂是其迈向产业化的基本要求。与无机半导体光催化剂和有机光催化剂相比，金属-有机框架（MOFs）凭借其结构的明确性、内在多孔性和多组分杂化特性在光催化分解水制氢领域有着明显优势。本项目针对常规MOFs光催化剂水相稳定性差和光生电荷分离效率低的研究现状，基于金属-有机框架平台中配体与节点的分子级设计策略：1）在MOFs中构筑了Co4O4准立方烷结构片段（GXY-L8-Co）模拟了自然光合系统II的活性中心结构和功能；2）将捕光中心与催化中心直接结合构筑宽光谱捕光MOFs（Ni-TBAPy），极大的提高了电荷分离效率，在无助催化剂条件下实现了高效光催化分解水制氢性能；3）利用锆氧簇作为节点提高稳定性，开发了新型水相稳定宽光谱捕光MOFs催化剂：TPB-PhCOOH-Zr和GXY-L8-Zr（吸收带边可至560 nm）；4）通过研究MOFs材料结构与制氢性能之间的“构效关系”，为新型高效太阳能分解水制氢催化剂的拓展提供了相关理论认识。研究结果具有创新性和科学意义。