Highly sensitive and selective ethanol sensor based on Sm2O3-loaded flower-like ZnO nanostructure

In this investigation, the influence of Sm2O3 on the sensitivity and selectivity of ZnO flower-like sensors for selective detection of C2H5OH in the presence of CH4, CO and toluene is studied. Samples of ZnO loaded with 2, 5 and 10 wt% Sm2O3 were prepared by employing a microwave assisted method using aqueous solutions of zinc acetate, samarium nitrate, and guanidinium carbonate as a structure directing agent. The samples were characterized by SEM, EDX, XRD, DRS UV-vis, and BET surface area techniques. Hexagonal wurtzite structure of ZnO is formed for all the samples calcined at 600 °C. The sensors' responses were measured in presence of 500 ppm of CO, toluene, ethanol and 1.0 vol% of methane in air at 200-400 °C. As 5 wt% Sm2O3 is added to ZnO, significant enhancements in the response to ethanol at various temperatures are observed, while it shows negligible responses to CO, toluene and methane. At 300 °C, the response of 5 wt% Sm2O3-ZnO sensor to ethanol is 60 times larger than that of pure ZnO. The Sm2O3-ZnO sensors show no or little response to methane, toluene and CO.