Synthesis Of Novel Non-noble Metal Supramolecular Catalytic System And Their Application In Photocatalysis

Developing efficient photocatalytic system is an effective way to reduce dependence on fossil energy and alleviate environmental pollution.The homogeneous catalytic system usually consists of photosensitizer,catalyst and sacrificial agent components.In the traditional catalytic system,the photosensitizer and catalyst exist in the free form in solution,and the electron transfer between components is limited by the process of diffusion collision,so the electron transfer efficiency is low.To address the above limitations,traditional catalytic systems generally rely on precious metal photosensitizers or catalysts,which is not conducive to large-scale application.In view of the above limitations,a covalent bond coupling strategy and a dynamic coordination strategy were developed in this paper,which coupled the photosensitizer and catalyst at a short distance to accelerate electron transfer between components and achieve efficient CO₂ photoreduction and photohydrolysis hydrogen production.Specific research contents are as follows:Firstly,a covalent coupling strategy of photosensitized agent and catalyst was developed.A novel non-precious metal supramolecular catalytic system（F-B-1 and F-2B-1）was constructed by covalent coupling of iron tetrapyridine catalyst with anthracyl modified boron pyrrole（Bodipy）through Click reaction.When it is used for visible light driven CO₂ reduction,the TON of CO produced by supramolecular system F-2B-1 containing double Bodipy is up to 387.5,which is 10 times higher than the traditional free system and 1.5 times higher than the supramolecular catalytic system F-B-1 containing single Bodipy.Studies have shown that the covalent coupling of Bodipy photosensitizer with high efficiency iron based catalyst,which has strong visible light absorption and long excited state lifetime,can significantly improve the visible light absorption capacity,intermolecular and intramolecular electron transfer efficiency of the catalytic system,and thus greatly improve the CO₂photoreduction efficiency.Secondly,the dynamic coordination strategy of photosensitizer and catalyst was developed.The dynamic coordination between pyridinyl Bodipy photosensitizer and cobalt oxime catalyst was carried out to accelerate the electron transfer between components and improve the photocatalytic efficiency.Under visible light irradiation,the direct physical mixing of pyridinyl Bodipy and cobalt oxime catalyst was used to produce hydrogen by water decomposition.The hydrogen TON produced by pyridinyl Bodipy was more than 300,which was more than 15 times of the traditional free catalytic system.Importantly,the catalytic activity of the dynamic coordination system is 1.5 times higher than that of the system in which the photosensitizer is directly coordinated with the catalyst.The results show that dynamic coordination bonds can not only accelerate the electron transfer between components,but also effectively inhibit the excitation energy loss caused by electron-hole recombination.In addition,this kind of dynamic coordination system is easy to synthesize,which not only contributes to the construction of efficient photocatalytic system,but also contributes to the selection of elementary elements.This work provides important scientific reference for the development of efficient and practical molecular devices.