Theoretical Chemistry Study On Graphdiyne-based Dual-atom Electrocatalyst For N₂ And CO₂ Reduction

Graphdiyne is a new two-dimensional carbon nano material following graphene.It hasπ-πconjugated structure similar to graphene,and has many advantages such as large specific surface area,porous channel structure and excellent electron transport performance.Graphdiyne has been widely used in photo/electrocatalysis and new energy fields.Previous experimental and theoretical studies have reported that graphdiyne can be used as a substrate for electrochemical catalytic reaction,in which the large central cavity on the monolayer graphdiyne can provide adsorption sites for the catalyst and improve the catalytic efficiency of the catalyst.According to the literature research knowledge,previously for graphdiyne as basement of electrochemical catalytic research mainly concentrated in the single atoms on graphdiyne,However,there are some problems such as low load rate and single catalytic site,which hinder the further development of graphdiyne-based activation reaction of small molecules.In order to solve this research dilemma,a strategy of small molecule activation catalyzed by diatomic catalyst on graphdiyne substrate was proposed in this paper.Compared with single catalyst,diatomic catalyst not only enhances the load of catalyst,another advantage is diatomic catalyst in graphdiyne substrate adsorption mode will be more diversified,and can make use of heteronuclear diatomic interactions between the catalyst with single catalyst completely different properties.Firstly,we studied and discussed the catalytic performance of graphdiyne-supported diatomic catalyst（TM₂@GDY,TM=Mo,W,Nb,Ru）in the electrocatalytic nitrogen reduction reaction,and adopted density functional theory calculation,state density analysis,charge difference analysis,molecular dynamics simulation.Theoretical studies such as solvation calculation have confirmed that diatomic Ru supported on graphdiyne has a low rate-determining step free energy（0.55 e V）,which explains the application prospect of graphdiyne supported diatomic Ru catalyst in nitrogen reduction.Next,we use graphdiyne-based,supported homonuclear and heteronuclear diatomic catalysts（Cu Cu,Cu Fe,Cu Co,Cu Ni）for electrocatalytic reduction of carbon dioxide and explore their catalytic properties.We describe the changes in the reaction intermediates under microscopic conditions.By comparing the adsorption energy of different reaction intermediates and the energy barrier in different carbon dioxide product paths,it is concluded that Cu Co loaded on graphdiyne has the best methane-producing ability,and its rate-determined step energy barrier is only 0.35 e V.Our results show that the synergy between diatomic catalysts is beneficial to the adsorption and activation of inert small molecules on the catalyst surface,and it can effectively reduce the free energy of the rate-determining step in the catalytic reaction process,and improve the catalytic efficiency.The study shows that graphdiyne based diatomic catalysts have unique advantages in electrochemical catalytic activation of small molecules.