Catalytic Combustion-Type Hydrogen Sensor Using BaTiO3-based PTC Thermistor


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A catalytic combustion-type gas sensor using a positive temperature coefficient (PTC) thermistor, which shows a sharp resistance change around Curie temperature, was developed for the detection of hydrogen. La-doped BaTiO3 (Ba0.998 La0.002 TiO3) was prepared through a solid-state method and an oxalic acid method. La-doped BaTiO3 obtained by the oxalic acid method showed improved PTC properties, due to the formation of fine particles, as compared to that prepared with the solid-state method. The resulting sensor device showed a fairly high H2 sensitivity in the range of 100–1000 ppm. In addition, the H2 sensitivity and response speed were improved by coating a Pt/SiO2 catalyst on the sensor device because the catalytic combustion efficiency of H2 was improved by the catalyst coating.