Preparation of NiO–YSZ composite powder by a combustion method and its application for cathode of SOEC

Nickel oxide and yttria-stabilized zirconia (NiO–YSZ) composite powders were synthesized by a new situ-combustion method in this paper. The adding amount of CO(NH2)2 was calculated by the combustion reaction equation. The products were characterized by X-ray diffraction, field emission scanning electronic microscope and electrochemical impedance spectra (EIS). The results showed that the products were well crystallized with NiO coating on YSZ particles. The optimized ratio of CO(NH2)2 to Ni(NO3)2 was 2:1. A single solid oxide electrolysis cell made from NiO–YSZ composite cathode with the powder prepared at optimized ratio 2:1 exhibited better performance than other samples with the electrolytic voltage of 0.98 V. The electrolytic cell was operated steadily at 900 °C for 2 h with the current of 0.33 A cm−2 when the stream of 80% H2O + 20% H2 was input. EIS analysis indicated that H2O adsorption and diffusion of the Ni–YSZ electrode were the limited step in the whole electrolysis reaction.