| This work is focused on development of tungsten carbide-based materials as alternative anodes for direct utilization of methane in solid oxide fuel cells (SOFCs). Not only were the capabilities of the anodes highlighted, but the challenges were also stressed.;First, the impact of porous support microstructure on the electrochemical performance of infiltrated electrodes in SOFCs was investigated. Five distinctly different porous YSZ supports were developed and the influence of size, connectivity and distribution of the pores as well as the configuration of YSZ particles on the surface area and three phase boundary length was analyzed.;Next, the electrochemical characteristics and chemical stability of WC-based anodes were investigated. Two different cells were developed based on a conventional WC-YSZ composite anode and a WC infiltrated porous YSZ supported anode. It was shown that the former cannot be used as an alternative anode because of catastrophic changes in anode microstructure. The latter, however, performed rather stably with no catastrophic degradation. While WC-YSZ anodes were resistant to carbon formation under CH4, the fuel was poorly activated. Upon the addition of CeO2 and Ru promoters, the performance was remarkably boosted and the chemical stability of WC was highly improved.;Finally, cells based on Ni-CeO2-WC-YSZ anodes were studied. Symmetrical cell study showed that the Ni modified electrode performed stably with methane at 850°C under open circuit condition with no carbon formation. Moreover, the fuel cell results revealed that not only did the anode operate steadily with a reasonable performance in methane fuel, but the stability of the carbide phase was well maintained. The cell also successfully experienced an oxidation reduction recarburization cycle. This study indicates that the Ni modified WC-based anodes are compatible with methane fuel, giving reasonable and stable performance. |
