Titanium Dioxide and Tin Oxide Composite for so2 Gas Sensors

We present the synthesis and utilization of semiconducting metal oxide composites of SnO₂ and TiO₂ composites (ST) to serve as a SO₂ sensor for a range of applications including carbon capture and storage (CCS), enhance oil recovery (EOR) etc. ST-series pellets were prepared by conventional solid state synthesis approach (~700 ^oC in air), where the size of the pellet was ~1 cm in diameter. The chemical and thermal stability was demonstrated by employing scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD). The average grain size of as-prepared ST composites was obtained in few nanometers. The as-prepared ST pellets were tested for the sensing properties of SO₂ gas in ppm level. The effect of temperature was studied to optimize the operating temperature using Pt electrodes as current collector by applying a constant external potential (~100 mV). As-prepared ST2575 with 0.25 mol % SnO₂ exhibited an excellent sensing properties for SO₂ (10-40 ppm) at 450 ^oC. For the sensing measurements, SO₂ gas was diluted in N₂ gas by maintaining the total flow rate at 100 sccm. The t₉₀ (90% of response time) for ST2575 was found to be ~5 mins. The stability of the sensor was satisfactory for gas sensing measurements in optimized conditions.