A phosphate-based proton conducting solid electrolyte hydrocarbon gas sensor

A potentiometric sensor based on a proton conducting sodium phosphate solid electrolyte was utilized in conjunction with a hydrogenation catalyst to detect methane at 600 degreesC. By using a two-compartment cell with gold electrodes and H-2 gas, it was established that the solid electrolyte behaves as a proton conducting material, exhibiting Nernstian behavior. For sensing methane, Pt/CeO2 was painted onto one of the gold electrodes. Two cell designs, including a two-chamber cell with a reference gas, as well as a planar cell without a reference gas were examined for methane sensing. Pt/CeO2 prepared with colloidal Pt tested on the planar cell showed superior sensitivity to methane. A mixed potential behavior, arising from the combined effect of electrochemical reactions of methane and its oxidation products is proposed to give rise to the methane response. (C) 2002 Elsevier Science B.V. All rights reserved.