The Monitoring of H₂S and SO₂ Noxious Gases from Industrial Environment with Sensors Based on Flame-Spray-Made SNO₂ Nanoparticles

Abstract

The noxious gas sensors were developed successfully using flame-spray-made SnO₂ nanoparticles as the sensing materials. The functionalized nanoparticle properties were further analyzed by XRD, BET and TEM analyses. The SnO₂ nanoparticles (SSABET: 141.6 m2/g) were investigated revealing non-agglomerated spheroidal, hexagonal, rectangle (3 - 10 nm), and rod-like (3 - 5 nm in width and 5 - 20 nm in length) morphologies. The sensing films were prepared by spin coating onto the Al₂O₃ substrates interdigitated with Au electrodes. The sensing films were significantly developed in order to detect with H₂S (0.5 - 10 ppm) and SO₂ (20 - 500 ppm) at the operating temperature ranging from 200 - 350°C. After sensing test, the cross-section of sensing film was analyzed by SEM analyses. It was found that SnO₂ sensing film showed higher sensitive to H₂S gas with very fast response at lower concentrations (3 s, to 10 ppm). The cross sensitivities of the sensor towards different concentrations of H₂S, CO, H₂, and C₂H₂ were measured at 300°C. The sensor evidently shows much less response to CO, H₂, and C₂H₂ than to H₂S indicating higher selectivity for H₂S of the SnO₂ sensor at the lower concentration (10 ppm). In addition, the SnO₂ sensor was the most suitable candidate for the efficient detection of H₂S noxious gas.