Efficient ppt-Level H2S Gas Sensor Based on YSZ and α-Fe2O3 Nanofoam Sensing Electrode.

Herein, porous α-Fe2O3 nanofoam was successfully synthesized and used as a sensing electrode to fabricate a yttria-stabilized zirconia (YSZ) mixed-potential hydrogen sulfide (H2S) sensor for real-time monitoring of hazardous H2S gas. The sintering temperature was adjusted to modify the microstructure of the sensing electrode material and its electrochemical reaction intensity to H2S, enhancing the sensor's performance. Among the tested materials, α-Fe2O3 nanofoam sintered at 800 °C exhibited the highest electrochemical catalytic activity toward H2S in electrochemical tests, suggesting its suitability as a sensing electrode material for YSZ-based H2S sensors. The sensor incorporating α-Fe2O3 nanofoam sintered at 800 °C achieved the highest response of -273 mV to 10 ppm of H2S at 625 °C. Moreover, this sensor exhibited a low detection limit of 100 ppt and, within the H2S concentration range of 0.5-10 ppm, a high sensitivity of -180.3 mV/decade, outperforming other reported YSZ-based H2S sensors. Furthermore, this fabricated sensor exhibited excellent repeatability, selectivity, and long-term stability, indicating its potential for industrial safety early warnings and precise environmental monitoring. This study provides a valuable reference for designing porous sensing electrode materials and enhancing the sensing performance of mixed-potential gas sensor.