Porphyrins (Phthalocyanine) As Precursors For Preparation And Electrocatalyzed Hydrogen Evolution Reactions Of M-N-C Type Materials

The demand for energy is increasing rapidly with population growth and technological progress.At the same time,the air,water,soil pollution and the greenhouse effect caused by the widespread use of fossil fuels are not reduced,if this series of problems cannot be solved from the source,in the future the destiny of mankind and the sustainable development of the ecological environment cannot be guaranteed within next ten years.In order to better solve the environmental pollution problems caused by the burning of fossil fuels and petrochemical production,scientists are committed to find clean,efficient and stable alternative energy resources of fossil fuels.Hydrogen is considered to be the most potential energy source in the future due to its advantages of high combustion heat,sufficient raw materials,clean reaction end products,and zero carbon emissions.Recent studies have shown that the precious metal platinum has good catalytic activity in the hydrogen evolution reaction,but its low crust storage capacity leads to high prices and cannot be used commercially.It is of great practical significance to develop low-cost,high-activity catalysts to promote the successful applications of fuel cell technology.Compared with precious metals,transition metals have the advantages of rich crust content and low commercial price.At the same time,they exhibit excellent catalytic activity in electrochemical catalysis.In recent years,the use of transition metals to construct metal-nitrogen-carbon（M-N-C）catalysts has shown great potential and has received extensive attention from scientific researchers.At the same time,with deeper exploration,the MN₄ site is considered to have the best catalytic activity.Metal conjugated macrocyclic compounds,metal porphyrins,metal corroles and metal phthalocyanines have been widely used in electrocatalytic hydrogen evolution,oxygen evolution and oxygen reduction reactions,and show good electrochemical catalytic activity.At the same time,the inherent M-N₄-C structure in the molecular structure of the three-metal conjugated macrocyclic compounds is an excellent precursor for preparing M-N-C catalysts by the sacrificial template method.Based on the above theoretical foundation,the experimental work of this article is divided into four parts for research:1.Based on tetraphenyl cobalt（II）porphyrin,triphenyl cobalt（III）carbazole and cobalt（II）phthalocyanine as precursors,loaded with reduced graphene oxide,direct pyrolysis to prepare corresponding electrochemical catalysts for HER.The structure of the catalyst was characterized by spectroscopic technology,and its HER activity was finally tested in a 0.5M H₂SO₄ solution.The effect of different precursor ring structure sizes on the catalytic activity of the catalyst has been performed.2.Using tetraphenyl cobalt（II）porphyrin and other metal（Cu,Fe,Mn,Zn,Ni）porphyrins as composite precursors,loaded with reduced graphene oxide,direct pyrolysis to prepare bimetallic,nitrogen-doped catalysts.After the successful preparation of hetero-reduced graphene oxide catalyst was confirmed by spectroscopic characterization,it’s HER activity was tested to study the effect of bimetallic synergistic catalyst on the catalysis.3.Using pyrolyzed natural carbon material corn stover as carbon source,and the precursor loaded with tetraphenylcobalt（II）porphyrin,the corresponding catalyst was prepared by secondary pyrolysis,and characterized by spectroscopy and scanning electron microscopy.The electrochemical catalytic activity tests were also performed.4.Using bamboo leaves as a carbon source and supporting it with tetraphenylcobalt（II）porphyrin by natural diffusion,the corresponding catalyst was prepared by direct pyrolysis,and its microstructure was characterized by spectroscopy and scanning electron microscopy.Furthermore,the electrocatalysis was tested for HER activity.