Preparation Of Thiophene-substituted Co~Ⅲ-and Cu~Ⅲ Corroles Based Conductive Polymers And Their Hydrogen Evolution Behaviors

As one of the clean energy sources,hydrogen energy is expected to alleviate or even solve the current environmental and energy crisis.The exploration of efficient hydrogen evolution electrocatalysts is crucial to the development of hydrogen energy.At present,the industrialized electrocatalysts are noble metal catalysts,which are expensive and are not conducive to the promotion of hydrogen energy.Therefore,it is important to develop efficient non-precious metal catalysts.In recent years,the application of corrole in the field of photocatalysis and electrocatalysis has become more and more extensive.By designing the meso-andβ-position groups of the corrole,its catalytic performance can be regulated,making it more suitable for catalyzing hydrogen evolution.On the other hand,the conductive polymers have the lots of advantages including high conductivity and good stability,which have wide application prospects.In this paper,a series of thiophene-substituted metallocorroles are designed,which have the ability to polymerize.After electropolymerization,the polymers are functionalized on the electrodes and performed satisfied electrochemically catalyzed hydrogen evolution behaviors.The main research contents are as follows:（1）Two thiophene-substituted Co^Ⅲ corroles were synthesized,which enable the corroles to be polymerized by electrochemical polymerization.The structure of the corroles was characterized by means of nuclear magnetic resonance,mass spectrometry,and electrochemical methods so as to prove the successful synthesis of corrole.The polycorroles were characterized by electropolymerization,SEM,EDS,XPS and Raman to confirm the conductive polymers were successfully loaded onto the surface of carbon paper material.Different modified electrodes were obtained by changing the polymerization parameters,and the hydrogen evolution performance was tested and compared.Then,the optimal parameters for synthesizing conductive polymers for catalyzing hydrogen evolution were explored.In the end,the polymerization monomer was changed to explore the influence of polymer structure on hydrogen evolution performance.The results show that the optimal polymerization parameters are:100cycles,50 m V/s,and the linear polymer with a single structure has better performance.（2）Two thiophene-substituted Cu^Ⅲ corroles were synthesized and characterized,then the polycorroles were synthesized by electropolymerization and characterized.The Electrocatalysis behaviors was also tested and compared with Co^Ⅲ corrole polymer,so as to explore the effect of the change of central metal on the hydrogen evolution performance of polymers.At last,the Cu^Ⅲ corrole and the Co^Ⅲ corrole were mixed and copolymerized,and the molar ratio of the two types of corroles was changed to explore whether the cobalt-copper bimetallic center had a synergistic effect on the catalytic hydrogen evolution of the polymer.The results show that the poly-Cu^Ⅲ corole 2a has better performance,and the synergistic catalysis of cobalt-copper bimetal is not strong.（3）By changing the substituents of Co^Ⅲ corroles at 10-positions including pentafluorophenyl,4-methoxyphenyl and 4-nitrophenyl,these A₂B-type thiophene-substituted Co^Ⅲ corroles were synthesized and their conductive polymers were also prepared.The basic characterization of corrole proves the successful synthesis of the compound.The hydrogen evolution performance of modified carbon paper electrodes was tested to explore the influence of different 10-position groups.According to the different performances,the influence of the electronic structure of the corrole monomer on the hydrogen evolution performance of the polymer was investigated.The results show that the monomer can affect the polymer’s performance,and the introduction of electron withdrawing groups at the 10th position is more conducive to behaviors.（4）Three small thiophene compounds with increasing molecular length were selected:thiophene,bisthiophene and trithiophene,which were copolymerized with dithiophene cobalt corroles.Different modified electrodes were obtained by changing ratio,their hydrogen evolution properties were tested and compared.According to the amount of small molecular introduced,the optimal copolymerization ratio was explored.According to the different types,the influence of the length of small molecule on the hydrogen evolution performance of the conductive polymer was explored.The results show that a small amount of thiophene small molecule can improve the hydrogen evolution performance,and the longest molecules have the greatest improvement.