Theoretical Computational Simulation Of Co₂ Reduction Reaction At Solid-Liquid Interface

As CO₂ is a key energy carrier of the C energy cycle,and CO₂ reduction technology can simultaneously solve energy crisis and severe environmental problems,CO₂ reduction reaction has received extensive attention in recent years.As an electrode catalyst that can effectively reduce CO₂,Cu has received extensive attention from the scientific and industrial circles.However,the complexity and particularity of the CO₂ catalytic reduction system at the solid/liquid interface is that it not only has a high degree of complexity in the microstructure,but also involves the structure of the catalytic material,solution structure（such as the conformation of water under different polarization conditions）,numerous elementary reactions and multi-channel reaction network.At present,theoretical catalysis calculation simulation has encountered great challenges in all aspects ranging from theoretical methods to reaction mechanism simulation.We combine the current popular neural network potential energy surface global search method and the Poisson-Boltzmann equation homogeneous medium model to find the complex reaction network at the solid/liquid interface and the kinetic characteristics of the CO₂ reduction reaction to analyze different surface morphologies and electronic structures Influence on reaction thermodynamics and kinetics.It includes a series of complex networks,such as catalyst surface coverage at different potentials,adsorption of reactants,bond scission and bond formation reactions,search for reaction intermediates,search for transition states and product formation.We have studied in detail the reaction pathways,reaction intermediates and reaction transition states of Cu（110）and Cu（111）crystal plane CO₂electro-reduction to C1 products,and established the CO₂ reduction reaction network and reaction kinetics.（1）We calculated the activation and preliminary reaction mechanism of CO₂ on the H₂O/Cu（110）interface of Cu（110）surface.We combined real water and DFT/CM-MPB methods to study the CO₂ activation process of CO₂on the Cu（110）surface（with 16 Cu atoms in the surface layer）under different real water（n H₂O,n=10 and 42）environments.It is found that the short-range polarization of water（10 H₂O）with a few chemical centers and the electrostatic interaction in the long-range DFT/CM-MPB solution can effectively simulate CO₂ activation.On this basis,we calculated the preliminary reaction mechanism of CO₂^*reaction hydrogenation,that is,CO₂^*hydrogenation to generate COOH^*and HCOO^*reaction intermediates.It is found that the subsequent products of the COOH^*intermediate are mainly CO^*,and more importantly,it is found that HCOO^*is generated more favorably in kinetics,and the subsequent reduction reaction of this intermediate can generate H₂COO^*and further generate CH₂OH^*,H₂C^*and CH₃O^*.（2）The effect of H coverage on Cu（110）surface CO₂ electrolytic reduction reaction mechanism of C1 products,main reaction intermediates and reaction transition states are explored.The results showed that high H coverages（13/16 ML）would promote the reduction of CO₂.HCOO^*is the first key intermediate produced by the dissociation of carbon dioxide.HCOO^*will be further hydrogenated and reduced to produce H₂COO^*intermediate,H₂COO^*intermediate will be hydrogenated and dissociated to form CH₂O^*on the Cu（110）surface.CH₂O^*will be further reduced to produce C1 products such as CH₄,thus the path of methane formation is CO₂^*-HCOO^*-H₂COO^*-CH₂O^*-CH₃O^*-CH₃^*-CH₄;the path of methanol formation is CO₂^*-HCOO^*-H₂COO^*-CH₂O^*-CH₃O^*-CH₃OH.（3）On the basis of the Cu（111）solid/liquid interface model,the possible reaction paths and intermediates in the electrochemical reduction of CO₂ are studied by using density functional theory.For the COOH^*intermediate,it will be further reduced to form CHO^*and CH₂O^*,and then continue to be hydrogenated to form CH₄.However,methanol is obtained through further reduction of HCOO^*and H₂COO^*intermediates.Thus,our research results show that the path of CO₂ reduction to methane is CO₂^*-COOH^*-CO^*-CHO^*-CH₂O^*-CH₂OH^*-CH₂^*-CH₃^*-CH₄;the path of methanol formation is CO₂^*-HCOO^*-H₂COO^*-H₂COOH^*-CH₂O^*-CH₃O^*-CH₃OH.