Electrolysis of CO2 in a proton conducting membrane

The electrolysis of CO₂ is examined in a proton conducting solid electrolyser using BaCe_0.5Zr_0.3Y_0.16Zn_0.04O₃ − δ as the electrolyte, nickel as the anode to oxidize H₂O/H₂ and copper, nickel or iron as the cathode to reduce CO₂. The electrolyte and porous scaffolds were prepared by tape casting and the electrodes by impregnation. During electrolysis at 600ºC, currents as high as 35 mA/cm² (iron), 20 mA/cm² (copper) or 15 mA/cm² (nickel) at 1.5 V pass through the 200 μm thick electrolytes. Small additions of Pt improve considerably the performance of the electrodes. For iron based cathodes Faradaic efficiencies up to 100% are achieved with production rates of H ≈ 0.14 μmol/cm²s, HO ≈ 0.25 μmol/cm²s and CO ≈ 0.05 μmol/cm²s. The possibilities of increasing these yields are discussed.