金属有机框架平台整合光敏剂与多酸分子簇构筑分子复合材料及其光催化水分解活性研究

Design and synthesis of visible-light active stable photocatalytic materials with well-defined structure for water splitting into hydrogen and oxygen was one of the improtant way for the solar conversion and storage. Due to the well-defined composition and structure, it is easy for property tuning and possible to systematically explore the catalytic mechanism for the molecular catalysts. In this project, according to the structural model of catalytic active metal clusters in the PS system, we attempt to design and synthesize visible-light-driven molecular catalysts by assembling low-cost transition metal cations with lacunary POMs. Further, molecular composite photocatalytic materials could be obtained by integration of these POMs and the antenna molecules into the metal-organic frameworks (MOFs). The even distribution of the catalysts and photosensitizers in the MOFs and the spatial confinement effect of MOFs, will make the photoinduced charges quickly and efficiently transfer between them. The stability of the embeded photosensitizers will be much enhanced as the site isolation. Also, the immobiliztion of the catalysts and the photosensitizers into the MOF platform could prevnet the precipicate formation in the aqueous solution. In this project, we aimed to design and develop stable and efficient molecular photocatalytic systems, expore the catalytic mechanism, and further devote ourself to explore the molecular photocatalysts for overall water splitting.

构筑结构明确与稳定的可见光响应的光催化材料催化水解制氢与产氧，是实现太阳能转换与存储的重要途径之一。分子催化剂组成与结构明确，有利于性能调节与系统探索催化机理。本课题拟以光合系统中金属簇催化活性中心为模型，利用缺位多酸作为无机多齿配体组装廉价过渡金属离子构筑与筛选出可见光活性的分子催化剂。进一步利用金属有机框架材料组装的成熟技术将光敏剂分子与多酸簇共同整合于多孔材料中构筑分子复合光催化材料。催化剂与光敏剂分子在刚性骨架中均匀分布及金属有机框架材料空间限域效应可使光生电荷在限定区域内快速有效的传递；空间上的有效分离有望大大提高光敏剂分子的稳定性，并将有效避免均相催化中光敏剂与多阴离子易于生成沉淀的问题。旨在设计与构筑出高效稳定且易分离的分子光催化体系，探索催化机理，进一步致力于全水解分子催化剂的探索与开发。

本项目利用金属有机框架(MOF)材料将团簇催化剂与光敏剂整合，构建催化剂@光敏剂催化器件，提高太阳能利用率。以Preyssler型多酸团簇为前驱体，通过一步电化学沉积法制备超小Pt2W/WO3异质结团簇，用于高效驱动大电流分解水制氢。通过调控多酸的酸度，刻蚀金属氧化物载体，实现高效水分解产氧催化剂的合成。揭示了单原子聚集成核过程，分离出亚纳米fcc钌团簇。以双金属普鲁士蓝为前驱体磷化制备出层级多孔Fe-CoP电催化剂，在低过电位下 (<300 mV)驱动大电流 (>500 mA cm-2)水氧化反应，并且只需 1.49 V槽电压驱动高效全水解制氢与制氧反应。探索出固体溶液萃取策略，在FePOx基底上制备出精细的Ni2P纳米团簇与颗粒，构筑Ni2P@FePOx异质结用于高效全水解制氢。通过合成与筛选高稳定性MOF材料作为分子平台整合催化剂与吸光基团构建“催化剂@光敏剂”催化器件，加速光生电子转移效率。采用含氮配体与{Co3}团簇配位构建高稳定性 MOF平台[Co3(DCPN)2(µ3-OH)(H2O)]-，该材料可以在pH 2.0-12.0的水溶液中稳定存在。利用过渡金属取代型多酸团簇调整MOF电荷用于富集阳离子光敏剂[Ru(bpy)3]2+，构建多酸@光敏剂复合催化体系用于光催化产氢。利用MOF平台实现了钴单点催化剂与Ru(bpy)32+光敏剂在分子水平上的组装，合成催化剂@光敏剂复合催化体系用于高效光催化CO2还原与水分解制备特定比例的合成气。以石墨烯作为模板与电子传输介质，实现超薄金属有机层的合成与加速光生电子转移，可高效驱动CO2到CO光还原，CO产率高达3133 mmol g-1MOL，选择性高达95%。将构建催化剂@吸光材料催化器件的策略进一步拓展，分别以混金属MOF材料与普鲁士蓝配位聚合物为前驱体，通过硫化与热处理过程分别构建了催化剂@吸光材料异质结，同时实现高效光催化制氢与高附加值有机化学品的制备。