Theoretical Study On The Catalytic Performance Of Single-atom Catalysts For Nitrogen Reduction Reactions And Carbon Monoxide Oxidation Reactions

In recent years,great progress has been made in the research of single atom catalysts.The single atom catalysts have shown excellent catalytic performance for many important chemical reactions.The two-dimension material graphene has a large surface area and unique electronic properties,thus is widely used as a support material for a variety of single atom catalysts.Ammonia?NH₃?is a very crucial industrial feedstock that has been widely used in various fields.Haber-Bosch method is a traditional ammonia synthesis process,which has the disadvantages of high energy consumption,large amounts of carbon dioxide emission,harsh reaction conditions,etc.Therefore,searching for economic friendly methods on nitrogen fixation has become an aspirational goal for chemists.The reduction reaction of nitrogen can be performed at atmospheric temperature and pressure with the help of electrocatalyst.In the electrocatalytic system,the electrocatalyst plays a pivotal role.We systematically investigated a series of single metal atoms including Sc to Zn,Mo,Ru,Rh,Pd and Ag anchoring on the defective graphene surface for nitrogen reduction reaction by density functional theory?DFT?.Our DFT calculation results showed that single Mo atom supported on N-modified555-777 graphene surface is a potential nitrogen reduction reaction electrocatalyst.The overpotential value is calculated to be only 0.41 V.In particular,the removal of produced ammonia from the catalyst surface is a rapid process with free energies change of 0.45 e V.Electronic structure analysis showed that the ground state of single Mo atom supported on N-modified 555-777 graphene surface is highly spin-polarized,which is an important reason for its good catalytic activity.CO is a kind of toxic gas that is extremely harmful to environment and human.It is important to study the elimination of CO.At present,the low-temperature catalytic oxidation method of CO is an effective method for the elimination of CO.Noble metal catalysts are economically expensive.Non-noble metal catalysts can reduce cost and ensure good catalytic performance.Based on DFT,we select single Al atom supporting on the surface of N-modified graphene,and evaluate the catalytic performance of CO oxidation reaction.Our DFT calculation results showed that single Al atom supporting on N-modified graphene exhibits excellent catalytic performance for CO oxidation.The preferable reaction path is the ER-1 pathway with a quite low energy barrier of 0.27 eV.