Highly Selective and Fast Response/Recovery Cataluminescence Sensor Based on SnO for HS Detection.

In the present work, three kinds of nanosized SnO samples were successfully synthesized via a hydrothermal method with subsequent calcination at temperatures of 500 °C, 600 °C, and 700 °C. The morphology and structure of the as-prepared samples were characterized using X-ray diffraction, transmission electron microscopy, selected area electron diffraction, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy. The results clearly indicated that the SnO sample calcined at 600 °C had a higher amount of chemisorbed oxygen than the SnO samples calcined at 500 °C and 700 °C. Gas sensing investigations revealed that the cataluminescence (CTL) sensors based on the three SnO samples all exhibited high selectivity toward HS, but the sensor based on SnO-600 °C exhibited the highest response under the same conditions. At an operating temperature of 210 °C, the SnO-600 °C sensor showed a good linear response to HS in the concentration range of 20-420 ppm, with a detection limit of 8 ppm. The response and recovery times were 3.5 s/1.5 s for HS gas within the linear range. The study on the sensing mechanism indicated that HS was oxidized into excited states of SO by chemisorbed oxygen on the SnO surface, which was mainly responsible for CTL emission. The chemisorbed oxygen played an important role in the oxidation of HS, and, as such, the reason for the SnO-600 °C sensor showing the highest response could be ascribed to the highest amount of chemisorbed oxygen on its surface. The proposed SnO-based gas sensor has great potential for the rapid monitoring of HS.