Enhanced sulfur and carbon coking tolerance of novel co-doped ceria based anode for solid oxide fuel cells

Doubly doped CeO ₂ based anode with Y and Yb is first reported for direct methane solid oxide fuel cells. The power output of the cell with Ni-Ce _0.8Y _0.1Yb _0.1O _1.9 anode and stability at various temperatures are investigated when air is used as oxidant and pure H ₂, 5 ppm H ₂S containing H ₂ and dry CH ₄ as fuel, respectively. At 750 °C, the cell displays stable power output for 120 h at 200 mA cm ^-2 when fueled with dry CH ₄, suggesting the carbon deposit is largely absent on the anode, which is confirmed by the SEM observation and EDS results. The results also prove that the rare earth elements Y and Yb affect the sulfur tolerance performance of the anode in a cooperative fashion leading to good anode stability in the contaminated fuel. The SEM and EDS results provide evidence that the cell with Ni-Ce _0.8Y _0.1Yb _0.1O _1.9 anode is tolerant toward the H ₂S contamination. The remarkable performances suggest that co-doped CeO ₂ anode is an attractive electrode component for direct hydrocarbon solid oxide fuel cells and might also be used as a catalyst for reforming of hydrocarbon fuels and for removal of fuel gas contaminations such as sulfur.