Tin-Zinc oxide composite ceramics for selective CO sensing

Composite metal oxide gas sensors were intensely studied over the past years having superior performance over their individual oxide components in detecting hazardous gases. A series of pellets with variable amounts of SnO2 (0-50 mol%) was prepared using wet homogenization of the component oxides leading to the composite tin-zinc ceramic system formation. The annealing temperature was set to 1100 degrees C. The samples containing 2.5 mol% SnO2 and 50 mol% SnO2 were annealed also at 1300 degrees C, in order to observe/to investigate the influence of the sintering behaviour on CO detection. The sensor materials were morphologically characterized by scanning electron microscopy (SEM). The increase in the SnO2 amount in the composite ceramic system leads to higher sample porosity and an improved sensitivity to CO. It was found that SnO2 (50 mol%) - ZnO (50 mol%) sample exhibits excellent sensing response, at a working temperature of 500 degrees C, for 5 ppm of CO, with a fast response time of approximately 60 s and an average recovery time of 15 min. Sensor selectivity was tested using cross-response to CO, methane and propane. The results indicated that the SnO2 (50 mol%)-ZnO (50 mol%) ceramic compound may be used for selective CO sensing applications. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.