Preparation Of Fe-based Catalysts And Application In Electrocatalytic Synthesis Of Amino Chemicals

The cycle of nitrogen,the mutual conversion of nitrogen-containing elements,has important significance in the cycle of natural elements and occupies a very important position in social development.Simultaneously,the fixed nitrogen is the main nutrient limiting plant growth in nature,thus sustainable production of amino chemicals（such as ammonia,nitrate,and urea）,has been an important challenge globally.In the next three decades,the demand for amino chemicals will only continue to increase to match global population growth.Currently,electrocatalytic nitrogen conversion,as an emerging process of green environmental protection and low energy consumption,has great potential for future development.Among them,the synthesis of targeted,efficient and stable electrocatalysts is the core step in the electrocatalytic synthesis of amino chemicals.Based on this,the main research contents and achievements of this paper are as follows:（1）A carbon-encapsulated mixed-valence Fe₇（PO₄）₆@C catalyst was prepared by a combination of a simple hydrothermal method and high-temperature calcination and applied in electrocatalytic nitrogen reduction（ENRR）.In electrochemical tests,a dramatic Faradaic efficiency（FE）of 36.93%and an NH₃production rate of 13.1μg·h^-1·mg_cat^-1were obtained at-0.3 V（vs.RHE）.Experiments and DFT calculations revealed that the superior performance was ascribed to the unique mixed-valence iron pair.The mixed-valence iron could break the linear correlations for collaborative hydrogenation and*NH₃separation to improve the kinetics of ammonia.（2）A Fe₃（THT）₂catalysts were successfully prepared by ammonia-assisted and solvothermal synthesis using THT as ligands and Fe（OAc）₂as central metal ions applied in electrocatalytic NO₃^-/CO₂reduction to synthesize urea.The experimental results showed that the catalyst obtained a urea synthesis rate of 68.31μg h^-1mg_cat^-1and a Faradaic efficiency of 5.31%at-0.7 V,and achieved a partial current of 39.59μA cm^-2.In this experiment,metal-organic materials were used for the first time for electrochemical urea synthesis and obtained reasonable catalytic activity.