Enhanced SO2 response based on morphology evolution and oxide precipitation in mixed-potential sensors with AVO4 (A=Ce, Sm) as sensing electrode

To fulfill the real-time monitoring requirements for the high SO 2 concentrations in industrial emissions, yttria-stabilized zirconia (YSZ)-based mixed-potential SO 2 sensors with rare-earth vanadates (AVO 4 , A = Ce, Sm) as sensing electrode materials were investigated in this work. The microstructure of the AVO 4 electrode was tuned by adjusting the corresponding sintering temperature (800-1100 °C), reaching the optimal match between particle size and pore structure at 1000 °C. The CeVO 4 sensor sintered at 1000 °C exhibited the best performance at the operation temperature of 400 °C, in which its polyhedral structure and the formation of CeVO 4 /CeO 2 heterointerfaces enhanced the diffusion and adsorption of SO 2 , achieving a response of -69.73 mV for 500 ppm SO 2 and a sensitivity of -25.92 mV/decade for 50-500 ppm SO 2 , significantly higher than that of the SmVO 4 electrode (-18.87 mV, -12.81 mV/decade). Additionally, the sensor can be operated at a wide temperature range from 400 °C to 600 °C. The response/recovery times were significantly shortened to 31 s/45 s (100 ppm) and 11 s/33 s (500 ppm) at 600 °C, approximately 90% faster than those of 400 °C, while maintaining a sensitivity of -13.06 mV/decade for 50-500 ppm SO 2 . Furthermore, the sensor exhibited excellent repeatability and long-term stability at 600 °C, which remained stable for 18 days with a slight response variation of < 8%. This study provides novel material design and optimization strategies for developing high-sensitivity SO 2 sensors with a wide detection range and rapid response ability, which are capable of operating under harsh industrial conditions.