基于蜜勒胺基MOF碳氮材料的可控制备及其光电催化性能研究

Carbon and nitrogen materials are asked for suitable band structure, rich active sites and efficient carrier separation as active catalysts in photoelectrocatalysis. Facing to these high demands, a MOF precursor with regulable element composition and distribution among carbon, nitrogen and metal is willing to be first fabricated. Afterwards, the corresponding carbon and nitrogen materials will be generated and applied in the field of photoelectrocatalytic hydrogen production. The aims of the proposed study consist of two points, first, to analyze the effection of metal species, states and coordination modes on the structure of melem based-MOF, secondly, to elucidate the photocatalytic activity of carbon and nitrogen materials as a function of their structural, chemical, and physical properties. More specifically, we would like to construct the melem based-MOF via the combination of addictive reaction and ion exchange, study the fabrication process. Alter the bonding configurations of nitrogen, metal species coordination modes to control the synthesis into well-defined materials. Advanced characterization tools will be used to study the carbon and nitrogen materials’ morphology, structure and atomic composition, aiming to develop generation mechanism. The photoelectrocatalytic activity of the carbon and nitrogen materiasl will be evaluated with the properties of their surface and interfaces as well as the carriers’ separation efficiency. Moreover, the hydrogen adsorbing-desorbing ability of the metal center and structural nitrogen sites will be studied via DFT calculation, providing a theoretical support to construct photocatalytic materials in the future.

项目针对高活性碳氮材料在能带结构、活性中心、载流子分离效率等方面的高要求，拟设计并构建碳、氮、金属元素比例和分布可控的MOF材料作为前驱体，并研究基于该MOF制得的碳氮材料的光电催化性能。围绕金属源的种类、价态、配位方式对蜜勒胺基MOF材料微结构的影响，碳氮材料的微观结构与催化性能间的构效关系等关键科学问题，拟开展以下研究：通过加成反应与离子交换构建蜜勒胺基MOF材料，研究其形成过程；对氮元素的键合构型、金属源和配位方式等关键要素进行调控，建立碳氮材料形貌和结构可控的制备方法；对碳氮材料形成过程中的形貌、结构、原子组成等信息进行表征，据此推断其形成机理和演变规律；面向光电催化产氢，研究制得碳氮材料的表界面特性、光生载流子分离效率和催化性能，并阐明其反应原理。此外，本项目还将通过密度泛函计算金属中心和碳氮材料结构对氢原子的吸附/脱附能力，为探索和设计高性能的光电催化材料提供理论支撑。

针对碳氮光/电催化剂在能带结构、活性中心、载流子分离效率等方面的高要求，项目设计并构建了碳、氮、金属元素比例和分布可控的蜜勒胺基MOF材料，进一步基于金属源的种类、价态、配位方式对蜜勒胺基MOF材料微结构的影响，实现了具有高光/电催化活性的系列碳氮材料的制备。主要工作如下：（1）通过二氰胺钠与二氰二胺的环化加成反应制备6-取代-2,4-二氨基-1,3,5-三嗪单体，经过进一步缩聚反应得到富含氰基缺陷的Na掺杂氮化碳，研究了氰基缺陷与Na对氮化碳光催化分解水析氢性能的影响。（2）以氰胺一钠和二氰二胺为原料，通过环化加成反应制备了具有支链为氨基钠盐的Na-triazine结构，通过进一步的低温缩聚反应，得到具有四个三嗪环单元的聚三嗪钠盐Na-PTI，合成包括镍、钴、铁、钼等多种单金属和双金属的二维MOF材料，其具有优异的电催化产氧性能。（3）以聚三嗪钠盐Na-PTI和乙酰丙酮钼为原料，通过离子交换制备Mo-PTI纳米带，进一步退火后得到化学计量型的Mo2CN/NC纳米棒催化剂，通过理论计算、物性表征以及电化学测试，结果表明间隙空位的消除和晶格碳原子对间隙空位的取代调节了金属钼原子的轨道杂化形式和电子云分布，优化了水分子吸附解离的同时构建了新的氢物种的吸附活性位点，实现了高效碱性析氢催化剂的构建。