Study On The First Principle Of CO₂ Hydrogenation Catalyzed By Copper Single Atom

The resource use of CO₂ is an important way to address the greenhouse effect and energy shortages.Hydrogenation of CO₂ into the high value-added chemical methanol is an ideal strategy for converting and storing CO₂,which is highly productive in industrial production.and application value.The catalysts used in this reaction are mainly loaded Cu-based catalysts,which have the problems of harsh reaction conditions,selectivity and low conversion.Single atom catalysts?SACs?offer high catalytic efficiency,high performance and low cost of ownership.The advantages of structural stability and extremely high atomic utilization have attracted much attention from researchers in recent years.The key to the preparation of SACs by experimental methods is to achi eVe atomic-l eVel dispersion of the metal precursors,which can be generally achi eVed by spatially limited domains,defects Capture,alignment anchoring,and other strategies are carried out.In this paper,we adopt the density functional approach in first principles and use the DMol₃ module in the Material Studio package to construct carrier defects and coordination anchor points from a theoretical point of view to construct nitrogen-doped defective graphene-loaded Cu monatomic catalysts for the CO₂ hydrogenation to methanol reaction,as follows:?1?Based on the construction of a perfect graphene model,single/double vacancy-defective graphene and N-doped graphene models were constructed,and finally N-doped graphene adsorbing a single Cu atom,i.e.,loaded Cu single-atom catalyst models,were constructed.Geometric optimization calculations are performed on all models to further calculate the Cu atom binding energy and electronic structure and analyze their stability.It was found that the adsorption of Cu atoms on single vacancy-deficient N-doped graphene is unstable,with Cu atoms protruding from the graphene plane;the double vacancy The adsorption energies of the defective nitrogen-doped graphene on Cu monoatoms are negative,indicating that it can be stably adsorbed on the carrier and the Cu atoms are embedded in the substrate.In the plane,the two N-doped long-edge neighbors of the structure have the largest adsorption energy for Cu atoms,reaching-3.349 eV.The density analysis shows that the Cu atoms are mainly anchored to the substrate by hybridization with their C and N neighbors.The density analysis shows that the Cu atoms are mainly anchored to the substrate by hybridization with their neighboring C and N atoms.Mulliken bucolic analysis indicates that Cu-N interactions are the main factor in the anchoring of single atoms to the carrier.?2?The most stable Cu monoatomic catalyst model,i.e.,a structure adsorbed to a double vacancy defect doped with two N long-edge neighbors,was selected by different The reaction paths,heat of reaction and reaction energy barrier are calculated to clarify the reaction paths and mechanism.Three reaction paths are selected for the calculation,path one is the hydrogenation of CO₂ to obtain HOCO*,HOCO*continues to hydrogenate to obtain COHOH*,COHOH*with OH*removed to give COH*,COH*continuously hydrogenated to give H₃COH;pathway Second,continuous hydrogenation of CO₂ gives HCOO*and HCOOH*,and then OH*is removed to give HCO*,HCO*is continuous Hydrogenation gives CH₃OH;path three is CO₂ deoxygenation to give CO,and continuous hydrogenation of CO gives HCO*,HCO*,HCO*,and HCO*.HCOH*and CH₃OH.path III is the optimal path by calculating the heat of reaction,and the heat of reaction energy is only 0.33 eV.;the transition state search results indicate that path 1 is the most likely response path,with a transition state energy barrier of4.62 eV,and that paths 2 and 3 have The energy barriers are 4.66 eV and 5.78 eV,respectively.integrated analysis of thermodynamic and kinetic results shows that path one is a single Cu Atomic catalysts catalyze the most likely reaction path for the CO₂ hydrogenation to methanol reaction.