Study On The Mechanism Of Nitrogen-Doped Carbon-based Heteronuclear Diatomic Electrocatalytic Reduction Of CO₂

The energy structure of"rich coal,lean oil,and less gas"makes coal-fired power generation still dominate the power production.Coal-fired power stations emit a large amount of CO₂ gas while meeting the power supply needs of the rapid economic development.Electrocatalytic reduction of CO₂ is an effective technical route for carbon emission reduction.Under the national"30·60"carbon emission reduction policy,it is imperative to develop new and efficient CO₂ electrocatalysts.Therefore,this paper uses density functional theory to study the catalytic activity of seven carbon-based FeCu bimetallic catalysts for electrocatalytic reduction of CO₂.First,the stability,geometric parameters and electronic structure of seven FeCu bimetallic catalysts were systematically studied.By calculating the binding energy between the metal atom and the carbon-based support,it is shown that the binding energy of the seven catalysts is greater than-10 eV,and has good thermodynamic stability;Based on first-principles molecular dynamics simulation calculations,the bond length and energy fluctuation values of the seven catalysts within 10 ps at 298.15K are less than 0.06（?）and 3 eV,respectively,indicating that the catalyst should have good kinetic stability.Through the analysis of geometric parameters such as bond length and lift height,the effect of nitrogen doping on the geometric structure of the catalyst is studied;Through the analysis of electronic structure properties such as charge density difference map,Bader charge,and projected density of states,the process of metal atoms embedded in carbon-based carriers and the electron transfer characteristics of the catalyst are studied.The number of electron transfer will increase with the increase of the number of doped nitrogen atoms,and nitrogen doping will change the electronic density of states distribution of the catalyst near the Fermi level.Then,the catalytic selectivity of the catalyst was analyzed,the reaction path of the electrocatalytic reduction of CO₂ was explored,and the catalytic activity volcano graph model was constructed to predict the lowest reaction energy barrier for the electrocatalytic reduction of CO₂ to generate methane.By calculating the Gibbs free energy changes of*H,*COOH and*HCOO on the catalyst,it is found that the catalyst has high selectivity for CO₂ reduction.Based on the standard hydrogen electrode model,it is found that the reaction pathways of formic acid,methanol and methane exist in the electrocatalytic reduction reaction of CO₂,and the optimal reaction pathways for the reduction of CO₂ to formic acid,methanol and methane by different catalysts are discussed.Using*HCOO binding energy and system electronegativity as descriptors,the proportional relationship between*HCOO binding energy,system electronegativity and*HCOO binding energy was established respectively,and the active volcano graph model with products of formic acid,methanol and methane was established.Based on the active volcano graph model,it is found that*HCOO+H⁺+e^-→*HCOOH is the potential determining step.The FeCu bimetallic catalyst doped with six nitrogen atoms has the highest catalytic activity,and the energy barrier for reduction to methane is 0.91eV;When the electronegativity is 30,the reaction heat of the final reaction step is 0.54eV,and its catalytic activity is equivalent to that of some noble metal catalysts.The research results can provide theoretical guidance for the development of cheap and efficient electrocatalytic reduction catalysts for CO₂.