Li- and na-doped NiO thick film for thermoelectric hydrogen sensor

A novel thermoelectric gas sensor of Li- and Na-doped NiO thick film coated with Pt as catalyst on half of its surface, was fabricated for hydrogen gas detection. When this sensor is exposed to air mixed with hydrogen gas, the catalytic reaction heats up the Pt-coated surface, and thermoelectric voltage appears across the hot and cold regions of the oxide film. The thick oxide film was printed on the alumina substrate with a viscous paste, a mixture of the nickel oxide powders doped with alkali ions and organic vehicle. The printed film was fired at 1000degreesC for 2 h and then the Pt thin film was deposited at room temperature by the rf sputtering method. The non-contact in situ temperature monitor used in this study enables the measurement of voltage signal and the temperature difference separately. The calculated thermopower of the thick oxide film is also discussed.