SO₂ gas sensor based on Ag-Ag₂SO₄-BaSO₄ sensing electrode

A sulfur dioxide (SO₂) gas sensor based on a novel structural sensing electrode was fabricated. The sensor consists of yttria-stabilized zirconia as the oxygen ion conductor, silver sulfate-based salts as the auxiliary phase, a silver/platinum mixed paste as the sensing electrode/catalyst, and a platinum paste as the reference electrode. Ball milling was employed to decrease the particle size of the silver sulfate-barium sulfate (Ag₂SO₄-BaSO₄) auxiliary phase. After the Ag₂SO₄-BaSO₄ mixture ball-milling for 20 h, the as-obtained sensor showed the highest sensitivity to SO₂ gas. Furthermore, in order to optimize the sensing electrode, particles of metallic silver were mixed with silver sulfate-based salts, and the as-designed sensing electrode displayed an improved sensitivity to SO₂ gas at a low temperature (400 °C).