HIGH-SENSITIVITY AND SELECTIVITY OF AN SNO2 SENSOR TO H2S AT AROUND 100-DEGREES-C

The effect of preparation conditions on the sensitivity of tin-oxide-b ased semiconducting gas sensors has been studied by appropriately engi neering the base material. The incorporation of CuO as an additive has significantly improved the sensing character of the sensor element. T hese sensor elements have been made sensitive to low concentrations (a bout 10 ppm and less) of hydrogen sulphide in air. Further, the operat ing temperature for maximum sensitivity has been considerably reduced to about 90-100 degrees C. These elements have been tested for cross s ensitivity to other gases and confirmed unambiguously to be specifical ly sensitive to H2S, which is detected with maximum sensitivity. A pla usible mechanism is proposed to explain this behaviour.