Improved activity of oxygen in Ni–Ce0.8Sm0.2O2-δ anode for solid oxide fuel cell with Pr doping

Abstract

Ni–Ce0.8PrxSm0.2-xO2-δ (x = 0–0.15) is studied as an anode of solid oxide fuel cells. The doping of Pr facilitates the chemical oxidation of CH3OH on the ceramic phase because the strength of Pr–O bond is weaker than that of Ce–O bond. With the addition of Pr, the electronic conductivity of the ceramic phase increases in an oxidizing atmosphere but decreases in a reducing atmosphere. The electrochemical conductivity relaxation results indicate that Pr improves oxygen surface exchange coefficient and oxygen chemical diffusion coefficient of Ce0.8Sm0.2O2-δ simultaneously. The doping of Pr shows negligible influence on the performance of the cell fed with H2 due to the high reactivity of H2. However, the maximum power density of the cell with methanol as the fuel increases significantly with the addition of Pr in the anode, demonstrating the high importance of the oxygen activity of the anode when a less active fuel is used. A Ce0.8Sm0.2O2-δ-carbonate electrolyte-supported single cell with Ni–Ce0.8Pr0.1Sm0.1O2-δ anode shows a maximum power density of 792 mW cm−2 at 650 °C with methanol as the fuel.