Steam/CO₂ electrolysis in symmetric solid oxide electrolysis cell with barium cerate-carbonate composite electrolyte

A composite electrolyte, Zr doped BaCe_0.8Y_0.2O_3-δ (BaCe_0.5Zr_0.3Y_0.2O_3-δ, BCZY) and binary carbonates [(Li,Na)₂CO₃] (LNCO) was first applied to reduce CO₂ accompanied with steam electrolysis in solid oxide electrolysis cell (SOEC) at 600 °C, lower than which conventional SOEC composed by YSZ works in (usually above 800 °C). Electrolysis performances are improved due to sufficient steam feed at oxygen electrode side (30-110 ml/min). Steam electrolysis provides proton source for the reduction of CO₂. Application of composite electrolyte promotes proton transport and directly leads to H₂ even CH₄ production. To a certain degree, carbon resistance guarantees the symmetric SOEC operation at a lower bias potential of 0.5 V (vs.OCV) applied. A redox-stable and carbon-tolerant LSCM as symmetric electrode with a hybrid-ion-conducting composite electrolyte realizes the fuel synthesis by CO₂ reduction in proton-type solid oxide electrolyzer.