Tuning H2 Sensing Performance of Zirconia-based Sensor using ZrSiO4(+Au) Sensing-electrode

We are reporting here a potentiometric sensor by using yttria-stabilized zirconia (YSZ) as a solid electrolyte as well as zirconium silicate (ZrSiO4) added with Au as a sensing electrode (SE), for achieving sensitive and selective detection of hydrogen (H2). The addition of 10 wt.% Au into ZrSiO4-SE increased the sensitivity toward 100 ppm H2 at 500 °C, while lower responses to other examined gases were observed. The ability to detect H2 selectively was elucidated via polarization-curve measurements in air and in N2 and confirmed via gas conversion test. It was found that the sensitive and selective H2 behavior was due to a lower catalytic activity against the gas-phase oxidation of H2 than that of C3H6, in combination with a higher catalytic activity to anodic reaction of H2 than that of C3H6. The good agreement between the observed sensitivity and the estimated value from the polarization-curve measurements confirmed that the sensing mechanism is based on mixed potential model. The sensor using ZrSiO4(+ 10 wt.% Au)-SE demonstrated a linear relationship between sensitivity and H2 concentration on a logarithmic scale and was capable of detecting H2 concentration as low as 20 ppm at 500 °C under humid conditions.