Room temperature potentiometric sensor for hydrogen sulfide and sulfur dioxide based on a Zn-doped Na3Zr2Si2PO12 electrolyte

In this study, four sodium superionic conductors Na3Zr2-xZnxSi2PO12 (x = 0, 0.1, 0.2, 0.3) were used as solid electrolytes for planar mixed-potential gas sensors (Zn0, Zn1, Zn2, and Zn3 sensors) to detect hydrogen sulfide (H2S) and sulfur dioxide (SO2). The total conductivity of the Na3Zr2-xZnxSi2PO12 electrolyte first increased and then decreased with increasing Zn2 + doping. When doped with 0.2 mol of Zn2+, the electrolyte exhibited the highest total conductivity of 6.37 x 10- 5 S & sdot;cm- 1 at 25 degrees C, which was 14.2 times higher than that of the undoped electrolyte. At 25 degrees C, the response of the Zn2 sensor to 10 ppm H2S was-237.8 mV, which was 6.9, 2.1, and 5.8 times that of the Zn0, Zn1, and Zn3 sensors, respectively. A high response of-58.6 mV was obtained by the Zn2 sensor at 25 degrees C for 0.5 ppm H2S. In addition, the sensitivity to H2S at 25 degrees C was-150.9 mV/decade. In comparison with reported mixed-potential H2S sensors, the Zn2 sensor demonstrated significantly higher response and sensitivity at room temperature. Moreover, the Zn2 sensor responded to 10 ppm SO2 and H2S almost equally at 25 degrees C. The gas sensing behavior was discussed in terms of the variation of sodium ionic conductivity, Na3PO4 phase proportion, and ZnS formation under H2S or SO2 atmosphere. Additionally, taking the detection of H2S- contaminated environments as an example, a gas leakage detection and alarm platform based on the Zn2 sensor was designed. This study provides insights into designing and developing high-performance mixed-potential gas sensors for H2S and SO2 at room temperature.