Electrolysis of CO2 in a proton conducting membrane

•Simultaneous electrolysis of steam and CO2 in a proton conductor.•Syn-gas production rates of H2 ≈ 0.14 mmol/cm2s and CO ≈ 0.05 mmol/cm2s.•At 600 °C a 30 mA/cm2 current at 1.5 V can be passed using Fe as cathode.•Small additions of Pt improves the performance of the Fe and Cu electrodes.

The electrolysis of CO2 is examined in a proton conducting solid electrolyser using BaCe0.5Zr0.3Y0.16Zn0.04O3 − 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 600 °C, 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 H2 ≈ 0.14 μmol/cm2 s, H2O ≈ 0.25 μmol/cm2 s and CO ≈ 0.05 μmol/cm2 s. The possibilities of increasing these yields are discussed.