Theoretical Study On Coordination Atom Regulating Single-atom Copper Electrocatalytic Carbon Dioxide Reduction Reaction

In recent years,the massive burning of fossil fuels has produced carbon dioxide（CO₂）,which has led to a series of problems such as global warming and ocean acidification.As a raw material,CO₂ can be converted into chemical products or fuels,which can not only reduce the consumption of fossil energy,but also reduce the content of CO₂,thus reducing the environmental problems caused by CO₂.As the cost of electricity generation from renewable energy continues to decrease,electrochemical reduction has gradually attracted widespread attention.To achieve high-efficiency electrocatalytic CO₂ reduction,the selection of suitable electrocatalysts is particularly important.Recently,nitrogen-doped transition metal single-atom catalysts（M-N-C）have good catalytic properties and exhibit excellent activity due to their unique coordination structure affecting the electronic properties of metal atoms.The transition metal Cu is one of the most important CO₂RR electrocatalysts.The introduction of heteroatoms into nitrogen-doped transition metal single-atom catalysts can regulate the coordination environment of metal atoms,and the electrocatalytic activity of CO₂ reduction can be improved by adjusting the electronic structure of the central atom by adjusting the coordination atoms.In this paper,we systematically studied the effect of Cu-N-C catalysts on CO₂reduction ability through first-principles calculations,and improved nitrogen-doped copper by adjusting the types（B、O、S）and number of coordinating atoms.CO₂reduction capacity of atomic Cu-N_4-xM_x（x=0-4,M=B、O、S）catalysts.Firstly,the catalyst structure with different coordination atomic structure was studied in this thesis,and the formation energy,dissolution potential and molecular dynamics simulation of the structure were calculated to judge the stability of the structure,and the electronic properties of the catalyst were also studied.Secondly,the influence of catalysts with different coordination configurations on CO₂ reduction products was studied,and the U_L value was used as the criterion to analyze the CO₂ products,and the optimal generation path was obtained.Finally,the free energy of hydrogen evolution reaction（HER）was calculated,and the CO₂ activity and HER activity of the system were analyzed and compared.The results show that the coordination atoms can gradually increase the charge around Cu and retain more electrons,while the low-charge state can effectively improve the CO capture ability,facilitate electron transfer,and improve its electrocatalytic activity.By analyzing the free energy results of each elementary reaction in the CO₂ reduction reaction of the system,the limit potential of Cu-N₃B₁ is 0.439 V,which can effectively generate CH₃OH and CH₄,and the limit potential of Cu-N₁B₃ is 0.498 V,which can generate CH₃OH under.The limit potential of Cu-N_OO₄ is 0.771 V,which is favorable for the generation of CH₃OH or CH₄.These three catalysts are promising single-atom catalysts that can be further developed for the reduction of CO₂ to hydrocarbon products.The research of this topic will effectively improve the current situation of CO₂ reduction and realize the utilization of CO₂.