Study of steam electrolysis using a microtubular ceramic reactor

Steam electrolysis was carried out using a microtubular ceramic reactor with the following cell configuration: La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF)–Ce0.8Gd0.2O1.9 (CGO) electrode/CGO buffer layer/(ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (ScSZ) electrolyte/Ni-ScSZ electrode supporting tube. 10% H2/Ar gas was used as steam carrier gas, and 18% steam was supplied to the ceramic reactors. The cell performance was as follows: 1.43 V at 0.1 A cm−2 and 650 °C (Area specific resistance: 4.7 Ω cm2) or 1.37 V at 0.1 A cm−2 and 700 °C (4.3 Ω cm2). During steam electrolysis, hydrogen production proportionally increased with current density according to Faraday's law, and heat generation at a low current density was observed by an electrochemical technique. Voids and Zr diffusion from the ScSZ electrolyte were confirmed in the CGO buffer layer. Such factors near the surface probably influenced the increase in ohmic loss and electrode polarization.