Application of Noble Metal-TiO2 Schottky Barrier Diodes as Dissolved Hydrogen Sensor
Jun-ichi Tani, Nobuyoshi Hara, Katsuhisa Sugimoto
An application of noble metal-TiO2 Schottky barrier diodes to dissolved hydrogen (DH) sensors was examined in aqueous solutions containing 2.9×10-2-24.5 mass ppb DH at 300K. It was found that Pd-TiO2 diodes showed quantitative relationship between their response voltages and DH concentrations in the range of 2.9×10-2 to 1.5 mass ppb and they could work as DH sensors. Their 90% response times to DH concentrations were less than 3ks. They also had sensitivities to H+ ions, but the sensitivities were less than 10% of their sensitivities to DH. Pd-TiO2 diodes suffered from serious hydrogen embrittlement in solutions having higher DH concentrations. To improve this fault, Pd-Au and Pd-Ag alloy-TiO2 diodes were examined. As a result, a Pd-33 at% Ag alloy-TiO2 diode was found to have a good resistance to hydrogen embrittlement. Its sensitivity to DH concentration, however, slightly deteriorated with alloying Ag.