CO and ethanol dual selective sensor of Sm 2O 3-doped SnO 2 nanoparticles synthesized by microwave-induced combustion

Abstract

In the present investigation, the influence of Sm 2O 3 on the sensitivity and selectivity of SnO 2-based sensors for selective detection of CO and C 2H 5OH in the presence of CH 4 is studied. SnO 2 doped with 2.0, 5.0 and 10.0 wt% Sm 2O 3 samples were prepared employing a microwave-induced solution combustion synthesis using tin chloride. The samples were characterized by SEM, EDS, XRD and BET. The results indicate that samarium oxide inhibits SnO 2 crystal growth and enhances both sensitivity and selectivity of the sensors to CO and ethanol in the presence of methane. Upon addition of 2.0 wt% Sm 2O 3, the crystallite size of SnO 2 reduces from 4.3 to 2.9 nm. As SnO 2 is doped with 5.0 wt% Sm 2O 3 a significant enhancement in response to CO and ethanol was observed at various temperatures. At 200 °C, the 5.0 wt% Sm 2O 3-doped SnO 2 sensor response to 300 ppm CO is 16 times higher than that to 300 ppm ethanol. On the contrary, 33 times higher response to ethanol is observed at 300 °C. The 5.0 wt% Sm 2O 3-doped sensor shows no response to methane up to 350 °C. This way, at different temperatures, the sensor is selective to either CO or ethanol in the presence of methane.