Structure And Activity Of Potential-dependent M(M=Pt And Cu)(110) Surface Phases Revealed From Machine-learning Atomic Simulation

Electrochemical reactions usually occur in a unique reaction environment such as the solid/liquid interface.The reaction activity and behavior of the reactants at the interface largely depend on the atomic and electronic structure on the interface under the research conditions.An important feature of the solid/liquid interface.The properties of electrode materials,surface adsorption and potential conditions can all affect the structure and properties of the solid/liquid interface,and thus have a significant effect on the nature and speed of the electrochemical reactions occurring at the solid/liquid interface.Therefore,to deeply understand the thermodynamics and dynamics of the solid/liquid interface,it is necessary to understand the structure and properties of the solid/liquid interface.Only with intensively research on the interface can we achieve the goal of effectively controlling the reaction process and speed of the solid/liquid interface.It has become a challenging task to deeply explore the internal relations and laws of the solid/liquid interface microstructure and reaction performance.Based on the artificial intelligence method of machine learning and the Poisson-Boltzmann continuum solvation model,this thesis studies the adsorption and surface structure of the metal M（M=Pt and Cu）（110）surface under electric potential conditions.On this basis,further research on the activity of the reaction under different potential conditions.（1）Here we report the first theoretical attempt,by combining the machine-learning based global optimization（SSW-NN method）and modified Poisson-Boltzmann continuum solvation（CM-MPB）based on first principles calculations,to elucidate the potential-dependent structure evolution on a stepped Pt surface and its catalytic activity,in which the cyclic voltammetry（CV）curves are simulated to compare with experiment.We identify four Types of structure domains on Pt（110）,namely Type-Ia: ordered Pt（110）-（1×1）;Type-Ib: disordering of Pt（110）-（1×1）;Type-II: ordered Pt（110）-（1×2）（the missing-row reconstruction）and Type-III: reconstructed Pt（110）-（1×4）,and the formation mechanism of the key five-coordinate Pt（Pt5c）site generated by the surface reconstruction of Pt（110）at + 0.20 V vs.NHE was studied.And the formation mechanism of the key five-coordinate Pt（Pt5c）site generated by the surface reconstruction of Pt（110）at +0.20 V vs.NHE was studied.（2）By calculating different surface structures,and revealing the potential-dependence of the coverage of H atom adsorbate,the total passed charge and the CV of these Pt（110）surface domains.By comparing the simulated CV curve with the experiment,it is found that the surface reconstruction from Type-Ia to Type-Ib occurs at +0.20 V vs.NHE when the average H coverage is above 0.60 ML,which produces the key five-coordinated Pt（Pt5c）sites.At the same time,the hydrogen evolution reactions that occur on three different types of structures are calculated,the Pt5 c sites exhibit the superior activity for hydrogen evolution reaction（HER）and are the key species responsible for the high HER activity of Pt electrode.（3）The surface coverage of Cu（110）has been investigated under different potential conditions.On this basis,we further calculated the initial reduction process of CO under low potential conditions（1ML）.The results show that the primary reduction of CO is mainly generated* CHO,with further simulation,we found that *CH2O and *CHOH are more easily generated thermodynamically.The results show that the best reduction path for methane is*CO-*CHO-*CH₂O-*CH₂OH-*CH₂-*CH₃-CH₄.