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.