Design Of Nitrogenase-like High Performance Catalysts And Its Application In Electrocatalytic Nitrogen Reduction Reaction

Ammonia is one of the maximum yield chemicals around the world with about 500 million tons’output.It is widely used in various fields including agriculture,chemical production and pharmaceutical.Ammonia has high energy density and hydrogen content;it is also one of the most promising renewable power carriers.Today,ammonia synthesis still relies on the Haber-Bosch process,which requires the reaction to run under harsh conditions using fossil fuels.This process is environmental unfriendly and stand in the way of achieving the goal“peak carbon”and“carbon neutrality”.At present,people have found that electrocatalytic method can synthesize ammonia in close to environmental conditions.On the one hand,this method can reduce pollution and achieve green production,on the other hand,the reaction equipment can be flexibly stacked to achieve small scale production.However,it is still urgent to find more efficient and economical catalysts for electrocatalytic nitrogen reduction to break through the technical barrier.At present,common electrocatalysts for ammonia synthesis still have drawbacks,such as low catalytic efficiency,high price and poor selectivity.In the search for more efficient catalysts,we found that biological nitrogen fixation,the most common way of rhizosphere biological dialogue in nature,provides considerable nitrogen.We attempted to design a Chevrel phase FeMo₆S₈catalyst based on biological nitrogenase,and simulate the process of nitrogenase reaction by analyzing its catalytic mechanism.Surprisingly,the catalyst showed high efficiency and selectivity comparable to nitrogenase catalysis,with ammonia yield reaching 28.6μg h–1 mg_cat.–1 in acidic electrolyte solution and Faraday efficiency up to 42.8%at the same voltage.Experimental results confirm that the FeMo₆S₈catalyst can guarantee the ammonia yield and Faraday efficiency of more than 12 cycles without significant decline,and the electrocatalytic equipment can also guarantee the stable operation time of more than 100 h.Through experimental and simulation results,we found that the two single-metal precursors in the catalyst do not have high catalytic activity,which was in the same way that the catalytic process is difficult when there is only a single ferritin or a single molybdenum protein in the nitrogenase.Our work provides a new idea for the industrialization of electrocatalytic ammonia synthesis,which will have great potential in the future.