Sensing properties of solid electrolyte SO2 sensor using metal-sulfide electrode

Solid-state electrochemical sensor devices combined with a sodium ion conductor (Na5DySi4O12) disc and metal-sulfide sensing electrodes synthesized via solution routes have been investigated for the detection of SO2 in the range 20–200 ppm at 150–400°C. Among the various sulfide sensing electrodes tested, the metal-mono sulfide-based electrodes (NiS, CdS, SnS and PbS) gave good SO2 sensitivity at 300–400°C. The CdS-based solid electrolyte sensor element showed the best sensing characteristics, i.e., the EMF response was almost linear with the logarithm of SO2 concentration in the range between 20 and 200 ppm, with a 90% response time to 100 ppm SO2 of about 2–4 min at 400°C.