Steam electrolysis in a solid oxide electrolysis cell fabricated by the phase-inversion tape casting method

In this study, an asymmetric NiO-yttria-stabilized zirconia (YSZ) cathode substrate has been successfully fabricated by the phase-inversion tape casting method. 3-dimensional X-ray microscopy and subsequent analysis demonstrate that the NiO-YSZ substrates exhibit dual-layer structure: a thin sponge-like pore layer is supported on a thick finger-like macro-void layer. The electrochemical performance of the Ni-YSZ/YSZ/YSZ-LSM electrolyzer with this novel dual-layer cathode has been significantly enhanced. The electrolyzer exhibits an excellent current density of 2.3 A cm(-2) and a high H-2 production rate of 958 mL cm(-2) h(-1), at 800 degrees C and 1.5 V, and a polarization resistance of 0.25 Omega cm(2) at the open circuit voltage when the cathode and anode are exposed to 33 vol.% H2O-67 vol.% H-2 and ambient air, respectively, demonstrating that the thin sponge-like pore layer in the dual-layer cathode can provide sufficient electrochemical reaction sites for H2O reduction, while the thick finger-like macro-void layer can serve as the support for the electrolyzer and facilitate H-2/H2O transport in the cathode, reducing the cathode polarization resistance and enhancing the cell performance. (C) 2015 Elsevier B.V. All rights reserved.