Preparation And Electrocatalytic Nitrogen Reduction To Ammonia Of Poly(ionic Liquid)/Tetracarboxylic Iron Phthalocyanine Composites

Ammonia（NH₃）is an important intermediate and raw material in the pharmaceutical,chemical,and fuel industries.Currently,Haber-Bosch method is used to synthesize ammonia in industry,which was a synthesis reaction of H₂ and N₂ under a high-temperature and high-pressure.However,Haber-Bosch process produces a large amount of carbon dioxide that contributes to the greenhouse effect and other negative impact on the environment.Therefore,the development of new pollution-free methods for synthesizing ammonia has attracted widespread attention.Among the methods,the electroreduction method has significant advantages,such as the synthesis reacted at room temperature and normal pressure,the synthesis rate can be regulated by voltage,etc.Additionally,water is needed as a clean and pollution-free energy source.So,electrocatalytic nitrogen reduction to ammonia（e NRR）has become a hot topic in recent years.However,the e NRR also has many problems.For example,the selectivity for ammonia production（NRR）is much lower than that of hydrogen evolution reaction（HER）,the rate of ammonia production and Faraday efficiency still need to improve.Developing suitable catalysts to improve the selectivity of NRR,increase the NH₃ yield rate and Faraday efficiency is the key points in the field of e NRR.In this study,the poly（ionic liquid）s,poly（1-vinyl-3-ethyl imidazolium bis[（tri-fluoromethane）sulfonyl]imide）（PILs）,and iron（II）phthalocyanine tetracarboxylate（Fe Pc（COOH）₄）were synthesized.Then the Fe Pc（COOH）₄ was dispersed in Poly（Vi Et Im⁺Tf₂N^-）to prepare the electrocatalyst PIL/Fe Pc.The ionic liquid monomer Vi Et Im⁺Br^-,the polymerized ionic liquid Poly（Vi Et Im⁺Br^-）,Poly（Vi Et Im⁺Tf₂N^-）,Fe Pc（COOH）₄,and electrocatalyst PIL/Fe Pc were characterized by FT-IR,UV-Vis,XRD,XPS,¹H-NMR,EDS,SEM.The experimental results showed that these materials were all successfully prepared.Furthermore,Fe Pc（COOH）₄ and PIL/Fe Pc were both loaded onto carbon cloth as working electrodes to investigate their performance as electrocatalysts for electro-chemical nitrogen reduction to produce ammonia,respectivley.The indigo carmine method was used to detect the amount of ammonia,and the rate of ammonia production and Faraday efficiency（FE）were calculated.The experimental results showed that both Fe Pc and PIL/Fe Pc have the ability to realize electrocatalytic synthesis of ammonia.Among them,the catalytical rate and Faraday efficiency of PIL/Fe Pc wer e4.67μg _NH3 h^-1 cm^-2 and 23.22%,respectively,which were significantly higher than those of Fe Pc(2.40μg _NH3 h^-1 cm^-2 and 7.08%).Moreover,the synthesis method of the new electrocatalyst is simple,and it can be applied as a new electrocatalyst for the eNRR.