Selectivity of an Ag/BTO-Based Nanocomposite as a Gas Sensor Between NO₂ and SO₂ Gases

The novel Ag/BTO/TiO₂ nanocomposite was assessed for its gas-sensing capabilities toward hazardous gases NO₂ and SO₂. It exhibited p-type behavior with increasing resistance for SO₂ with a response and recovery time of ∼5 and ∼2 s, respectively, switching to n-type behavior when exposed to NO₂ with a response and recovery time of ∼20 and ∼250 s, respectively. Analyte gas concentrations from 0 to 220 ppm were taken for analysis. Selectivity analysis at room temperature revealed NO₂'s superior response of ∼20% above 180 ppm, compared to SO₂'s < 3% response at 180 ppm. NO_2(VC) achieved its highest response (∼45%) at 30 ppm and remained constant above 80 ppm, while SO_2(VC) peaked at ∼30% at 60 ppm but declined with increasing flow rates. Further, the increasing temperature led to an amplified response for NO₂, whereas SO₂ showed an increase in response after 180 °C. SO_2(VC) exhibited a significant response of ∼70% from 140 °C onward. Additionally, NO_2(VC) showed distinct peaks at 160, 250, and 290 °C with responses of 50, 65, and 80%, respectively. The calculated limit of detection values were 236 ppm for NO₂, 644.07 ppm for SO₂, 401.32 ppm for NO_2(VC), and 496.86 ppm for SO_2(VC).