A potentiometric SO2 gas sensor based on the Li3PO4-Li2SiO3 solid electrolyte thin film

A potentiometric sulfur dioxide (SO2) gas sensor based on the Li3PO4-Li2SiO3 solid electrolyte thin film was developed. The sensor was based on a galvanic cell O2, SO2, Au, Li2SO4-V2O5|Li3PO4-Li2SiO3|Au, SO2, O2. The Li3PO4-Li2SiO3 thin film was deposited on the Al2O3 substrate by RF magnetron sputtering, and the Au patterns were fabricated as the electrodes. The sensing electrode materials of Li2SO4-V2O5 with different dopants TiO2 and MgO were prepared, and as the ratio of Li2SO4:TiO2 is 1:1 (mol) with 5 wt. % V2O5 and 5 wt. % MgO, the sensor showed relatively good response characteristics to SO2 at 450 °C. Then, the sensor was further tested at the working temperature from 400 °C to 500 °C. The results show that the sensor has good response to SO2 at 400-450 °C, and the sensitivity is 90.15-57.19 mV/dec. The response and recovery times are 20-40 s and 2.5-4 min, respectively, when the gas concentration of SO2 increases from 10 ppm to 100 ppm and then decreases to 10 ppm. At 425 °C, the sensitivity is close to the theoretical values, and the final recovery potential of the sensor is almost consistent with the initial potential.