A novel Ni-CERMET electrode based on a proton conducting electrolyte

Based on the one-chamber fuel cell design by Iwahara a catalytic methane se nsor has been developed. The working principle of this sensor is based on t he difference in catalytic properties of two electrodes for the CO2 reformi ng reaction of methane. The sensor is based on a high-temperature proton co nducting electrolyte, i.e. SrCe0.95Yb0.05O3-alpha or CaZr0.9In0.1O3-alpha. At 500 degreesC a linear sensor response on the methane partial pressure ha s been found for a Ru/SrCe0.95Yb0.05O3-alpha/Pt cell. This cell, however, s hows poor long-term stability. The long-term stability of the Ru/SrCe0.95Yb 0.05O3-alpha/Pt cell is improved using a more stable electrolyte material, i.e. CaZr0.9In0.1O3-(alpha)(CZI10). Further improvement of the long-term st ability of the sensor is achieved using a nickel-CaZr0.9In0.1O3-alpha CERME T (Ni-CZI10) electrode. The sensor response of a Ni-CZI10/CaZr0.9In0.1O3-al pha/Pt cell is found to be linear at 600 degreesC and 700 degreesC, respect ively. The temperature dependence of both the Ru/SrCe0.95Yb0.05O3-alpha/Pt and the Ni-CZI10/CaZr0.9In0.1O3-alpha/Pt cell can be explained by the tempe rature dependence of the catalytic activity of the electrode materials used . This confirms that the obtained EMF is established by a catalytic activit y difference between both electrodes. The power output of a Ni-CZI10/CaZr0. 9In0.1O3-alpha/Pt cell is also determined. A combined sensor-fuel cell woul d have the advantage that it is able to detect the fuel concentration in th e gas and, therefore, correct in-situ for fluctuations in the fuel concentr ation. The power output of the Ni-CZI10/CaZr0.9In0.1O3-alpha/Pt cell, howev er, is found to be 0.01 mW . cm(-2). This low power output, with respect to values reported in literature for the one-chamber fuel cell, can be explai ned by the relatively thick electrolyte used, the electrode materials chose n, and the use of the reforming reaction of methane instead of the partial oxidation of methane. However, the feasibility of the combined sensor-fuel cell has been demonstrated. (C) 2001 Kluwer Academic Publishers.