The Structural Control For Surface And Interface Of Ceramic Electrode Based On SrTiO₃ And CO₂ Electrolysis At High Temperature

The perovskite oxides?ABO₃?with the mixed ionic and electronic conductive characteristics,especially La_0.2Sr_0.8Ti O_3+??LST?,are commonly used as cathode material for solid oxide electrolysis cell?SOEC?.The ceramic electrode LST is more stable comparing with traditional metal matrix composites like Ni-YSZ which is easily to be oxidized,however,its electrochemical performance is limited by its catalytic activity because it is far less than that of metal-based electrode.In order to optimize the performance of LST,this work increases the catalytic activity of ceramic electrode by constructing the active interface composing of ceramic and metal with in situ exsolve metallic nanoparticle,further enhances the performance of LST based materials as the cathode of solid oxide electrolysis cell for direct CO₂ electrolysis.In this work,the surface structure of ceramic electrodes is controlled by doping Mn or Cr in B-site of LST.The changes in the oxygen vacancy concentration,electrical conductivity and the direct electrolysis performance for CO₂ are studied.It can be found that the redox activity of Mn element is stronger than that of Cr element.The influence of the single metal-ceramic interface by the basis of Mn doping on the LST based cathode materials has been studied.The metallic Ni would be exsolved from the lattice after reduction at high temperatures,and a nanoscale interface consisting of oxide and metal was formed and the efficient metallic nanocatalyst was anchored in the surface of titanates.The presence of the interface was characterized by SEM and TEM.It was found that the conductivity of LST based cathode materials increased significantly with the establishment of Ni interface,and the CO yield,current density and Faraday efficiency also increased significantly.The Faraday efficiency almost reached 100%.Furthermore,the cathode materials containing alloy-ceramic interface are studied.The interfacial performance of electrode with alloy-ceramic interface is stronger than that of electrode with single metal-ceramic interface,and this indicates the beneficial effect of alloy effect on materials.The relationship between the surface activity and the oxygen vacancy concentration was studied,then the connection between interfacial activity and interface perimeter was also studie.This work provides a better choice for the cathode materials of the SOECs by the material design of electrode.