Sensing characteristics of aged zirconia-based hydrogen sensor utilizing Zn–Ta-based oxide sensing-electrode

• The sensor utilizes a novel Zn–Ta-based oxide sensing electrode material.
• Sensitive & selective H2 response after aging for 40 days (Δemf ≈ − 600 mV).
• Stabilized sensor exhibited 90% response time of 70 s to 100 ppm H2.
• Sensitivity is hardly affected by changes in O2 and water vapor concentration.

We report here the enhanced sensing characteristics to H2 for a potentiometric sensor using an yttria-stabilized zirconia (YSZ) solid electrolyte and a ZnO(+ 84 wt.% Ta2O5) sensing electrode (SE) after aging at 500 °C. The emf response toward 400 ppm H2 was found to gradually increase up to − 800 mV after 40 days operation (aging) and was stabilized at this value until the 90th day. The aged and stabilized sensor exhibited highly sensitive response to H2, with minor responses toward other examined gases such as NOx and HCs. The 90% response time toward 100 ppm H2 was approximately 70 s. The H2 sensitivity of the stabilized sensor was hardly affected by changes in water vapor as well as O2 concentration, with repeatable and reproducible responses to H2.

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