First-principles Investigation On Oxygen Adsorption,Dissociation And Diffusion On La/SrMnO₃（001） Surface

More and more attention has been paid on the field of clean, efficient distributedgeneration in recent years. At the same time, the solid oxide fuel cell is the most effectivedevice to transform hydrocarbon energy to electrical energy through the electrochemicalreaction. The solid oxide fuel cell （SOFC） was invented to transform the chemical fueldirectly into electricity. So, it is most appropriate SOFC cathode materials.Cathode/electrolyte interface restore the oxygen molecules to oxygen ions. The reaction is astrong oxidizing atmosphere; perovskite surface oxygen adsorption and diffusion mechanismof their electrochemical performance is very important. Analysis of reaction mechanism, theisotope tracer method (¹⁸O₂) found that O₂/LSC surface oxygen adsorption decide the cathodereaction rate. In other words, the first step of the adsorption reaction determines theperformance of the solid cathode materials. Therefore, using the first principles method basedon density functional theory. We study La/SrMnO₃electrical properties and conductivemechanism and compare La/SrMnO₃on （001） three exterior face of the adsorption of O atoms,and O₂molecules in each surface during the dissociation process, because it has importantpractical significance.We adopt VASP software to calculate lattice structure and electrical performance ofLa/SrMnO₃,using first-principle pseudopotential plane wave calculations and the NudgedElastic Band method based on density functional theory, to study the dissociation ofmolecular oxygen on La/SrMnO₃（001） surface and the subsequent diffusion of atomicoxygen into the magnesium substrate. We provide O₂molecules dissociation path on the outerMnO₂, LaO and SrO surface and the energy barrier, investigate diffusion processes of O atomon three outer surfaces La/SrMnO₃（001） by calculation for each position potential barrier andthe stability of the basic situation of the adsorption position. On this basis, we compare thevalues of the activation energies for the steps of dissociation, diffusion, and desorption,propose dissociation of O₂and release oxygen during surface rate-determining step. Finally,we propose that solid cathode material for the La/SrMnO₃as the first step in determiningperformance when the adsorption reaction provides a theoretical support for data.