A direct-methane fuel cell with a ceria-based anode

Fuel cells constitute an attractive power-generation technology that conver ts chemical energy directly and with high efficiency into electricity while causing little pollution. Most fuel cells require hydrogen as the fuel, bu t viable near-term applications will need to use the more readily available hydrocarbons, such as methane. Present-day demonstration power plants and planned fuel-cell electric vehicles therefore include a reformer that conve rts hydrocarbon fuel into hydrogen. Operating fuel cells directly on hydroc arbons would obviously eliminate the need for such a reformer and improve e fficiency. In the case of polymer-electrolyte fuel cells, which have been s tudied for vehicle applications, the direct use of methanol fuel has been r eported, but resulted in fuel permeating the electrolyte(1,2). Solid oxide fuel cells-promising candidates for stationary power generation-can also us e hydrocarbon fuel directly to generate energy, but this mode of operation resulted in either carbon deposition at high temperatures or poor power out put at low operating temperatures(3-5). Here we report the direct electroch emical oxidation of methane in solid oxide fuel cells that generate power d ensities up to 0.37W cm(-2) at 650 degrees C. This performance is comparabl e to that of fuel cells using hydrogen(6,7) and is achieved by using ceria- containing anodes and low operating temperatures to avoid carbon deposition . We expect that the incorporation of more advanced cathodes would further improve the performance of our cells, making this:solid oxide fuel cell a p romising candidate for practical and efficient fuel-cell applications.