Formation of Nano-porous Structure in a Cathode at the Interface between Pt Electrode and YSZ during CO2 Electrolysis at 1,000 °C

Abstract

AbstractThe electrolysis of CO2 was investigated using a simple Pt/YSZ/Pt cell (yttria-stabilized zirconia (YSZ)). The cell performance increased drastically after applying the overvoltage of 4.0 V for ~5 min. The current density increased 30 times at 1.4 V and 11 times at 2.0 V. Using a laser microscope and field emission scanning electron microscopy (FE-SEM), the structural changes of the surface of the Pt electrode and the interface between the YSZ and Pt electrode were investigated to understand the reaction mechanism at the cathode for increasing the cell performance. The results showed that the Pt electrode surface became smooth after the experiment. Moreover, the interface between YSZ and the Pt cathode greatly changed after the electrolysis experiment, while that of the anode showed only a minor change. The structure of the cathode interface consisted of a 1-μm-thick nano-porous Pt layer and a micro-porous structure comprising YSZ and Pt. These structures are involved in CO2 electrolysis. Possible elementary reactions are also presented in this paper.