La0.5Ba0.5Mn1-xCoxO3-δ (x < 0.4) with a perovskite structure is studied as a cathode material for solid oxide electrolysis cells. The exsolution of metallic Co from the perovskite in a reducing atmosphere is in situ investigated. Co improves the electrical conductivity of La0.5Ba0.5MnO3-δ in a reducing atmosphere, and facilitates the oxygen exchange reaction on the cathode surface. The cathode with in situ exsolved Co nanoparticles shows a high activity for both H2O and CO2 electrolysis. At 1.3 V, a single cell supported by a La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte layer achieves H2O electrolysis current densities of 0.46 and 1.01 A cm-2 at 700 and 800 °C, respectively. A high CO2 electrolysis current density of 0.88 A cm−2 is also obtained with the same cell at 1.2 V and 850 °C with a Faradaic efficiency exceeding 90 %. The cathode exhibits a high stability for H2O and CO2 electrolysis. The co-electrolysis of H2O and CO2 with the cathode is also studied.
- Co doping
- Solid oxide electrolysis cell