四齿氮配体骨架结构对铜配合物电催化水氧化性能的影响

Splitting water into hydrogen and oxygen driven by solar energy or electric power from renewable energy sources is the promising way to solve the problems of energy crisis and greenhouse effect. Because oxygen evolution reaction (OER) proceeds via a four-electron and four-proton transfer process, it requires high energy to drive the reaction; the OER is the rate-limiting step of overall water splitting. Therefore, development of cheap, efficient and robust water oxidation electrocatalysts is the key point for the production of hydrogen from water. Copper complexes are the most widely studied electrochemical molecule OER catalysts. Previous studies show that the complexes with various ligand structures display different catalytic properties, but there is a lack of systematic studies on the intrinsic relationship between ligand structures and catalytic performance. The influences of the dentate number and conjugate effect of ligands on the catalytic performance of copper complexes for OER have been studied in our previous work. In this project, we will study the influence of the backbone on the electrocatalytic properties of copper complexes for water oxidation. We conjecture that the coordination bond angle, the ring strain of backbone and backbone rigidity could impact the overpotential, activity and stability of molecular copper catalysts. The implementation of this project will give chance to better understanding the structure-function relationship of molecular catalysts and hence pave the way to highly performing OER catalysts.

利用太阳能或由可再生能源转化的电能将水裂解为氢气和氧气是解决当今世界能源危机和温室效应的理想途径。水氧化反应是一个四电子-四质子转移的复杂过程，需要较高的驱动力，是水裂解反应的限速步骤。因此，开发廉价、高效、稳定的水氧化电催化剂是目前能源领域需要解决的核心问题之一。铜分子催化剂是研究最为广泛的均相水氧化电催化剂，但是催化剂使用的配体种类繁多，结构各异，催化性能参差不齐，缺乏对配体结构和催化性能之间关联性的系统研究。我们前期的研究发现配体的齿数和共轭效应会对铜配合物的催化性能产生影响，因此我们推测可以通过调变配体骨架结构提高催化剂的水氧化性能。本项目将从铜配合物配位键键角、骨架环张力、骨架刚柔性三个角度出发，具体研究配体骨架结构与催化剂的过电位、催化活性和稳定性之间的相互联系。本项目的开展有助于深入理解催化剂结构和其功能之间的构效关系，为构建高效水氧化分子催化剂提供实验依据和新的思路。

如今，日益增长的能源需求和严重的环境污染迫使人们开发清洁能源替代传统的化石燃料。氢能是一种理想的替代品，主要通过水裂解的形式制备。水氧化反应由于需要克服很高的动力学能垒转移四个电子和四个质子，从而形成O=O键，被认为是整个总反应的瓶颈。因此，廉价、高效、稳定的水氧化催化剂的开发已经成为目前大规模制氢的核心问题。本项目针对铜分子催化剂的配体种类繁多，结构各异，催化性能参差不齐，缺乏对配体结构和催化性能之间关联性的科学问题，从配体骨架刚柔性、环张力、共轭结构三个方面入手，开展了配体骨架结构与铜配合物电催化水氧化性能之间构效关系的研究。研究结果表明，刚性骨架有利于降低过电位，柔性骨架则提高催化活性和稳定性；环己烷配体骨架的引入导致催化性能的整体提升；增强配体骨架共轭效应可降低过电位，但催化活性也会随之降低。该构效关系的研究为后续非贵金属水氧化分子催化剂的设计合成及结构优化提供了实验依据和理论指导。此外，本项目还开发了一种商品化的铜配合物应用于中性水氧化反应，具有廉价的成本和优异的水氧化性能，为降低分子催化剂成本和简化制备工艺方面提供了可借鉴的思路。