Improve Activity and Stability of Ni-Ce0.8Sm0.2O1.9 As the Anode of a Methanol Fuelled Solid Oxide Fuel Cell

Solid oxide fuel cells (SOFCs) are electrochemical devices those convert chemical energy in fuels directly into electricity. Compared with H 2 , commercial hydrocarbon fuels can be safely stored and are more readily available, which could reduce the overall operation cost. Therefore, direct electrochemical oxidation of hydrocarbons into electricity using SOFCs is appealing. However, there are many operational problems those still need to be solved. The typical NiO-YSZ anode material has excellent catalytic properties for fuel oxidation and good electrical conductivity, while it experiences serious carbon deposition with hydrocarbons as fuels. Therefore, there is a need for developing new kinds of carbon resistant SOFC anode materials for the utilization of hydrocarbon fuels. In this work, Mo is utilized to modify the Ni-Ce0.8Sm0.2O1.9 (SDC) anode. The NiO-MoO3-SDC anode materials are prepared by impregnation technique, which are reduced to SDC and Ni-Mo alloy phases in H2 atmosphere. SOFCs with Ni-Mo-SDC composite anodes are fabricated and tested with methanol as fuel. The addition of Mo into Ni–SDC anode effectively improves performance and stability of the single cell at 700 oC. The anode with a mole ratio of Mo to Ni of 0.03:1 (Ni-3Mo-SDC) exhibits the lowest polarization resistance. The cell with that anode and SDC-carbonate composite electrolyte exhibits a maximum power density of 680 mW cm-2 at 700 oC. The stability of the cell is enhanced with the increase of the content of Mo in the anode. In order to further improve the cell performance and stability, rare earth elements (La, Pr and Sm) are introduced into Ni-3Mo-SDC. The effects of La, Pr and Sm addition on the catalytic activity for methanol pyrolysis and coking resistance of the Ni-3Mo-SDC anode are examined. The electrochemical performance of the SOFC is enhanced with introducing La and Sm into the anode. The cell with La addition in the anode shows a maximum power density of 765 mW cm-2 at 700 oC with methanol as fuel. The addition of La, Pr and Sm into Ni-3Mo-SDC anode improves the stability of the cell, which is mainly attributed to the decreased amount of carbon deposition with a high graphitization degree.