Ethanol sensing property of -Fe2O3 Nanorods/ZnO nanoparticles composites
-Fe2O3 was synthesized via hydrothermal treatment at 140 C for 24 h using Fe(NO3)3.9H2O and Na2SO4 as the raw materials. ZnO was prepared by soft chemical process using Zn(NO3)2 and (NH4)2CO3 as precursors. Field emission scanning electron microscopy (FESEM) images showed that the as-prepared -Fe2O3 had rod-like morphology with the diameter of 30-50 nm and 200-300 nm in length, and the shape of ZnO was nanoparticle with the size of 20-30 nm. The -Fe2O3/ZnO composites were obtained by grinding -Fe2O3 NRs powder with ZnO NPs powder in various weight ratios (Fe2O3/ZnO = 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80). The gas sensing properties of composite films were tested with ethanol, LPG and ammonia, where the concentrations ranged from 250 to 2000 ppm and temperatures in the range of 300-400 C. -Fe2O3/ZnO composite corresponding to 60 wt.% of -Fe2O3 exhibited superior sensing characteristic towards ethanol vapor comparing to other samples. Its sensor response is 48, which is 3 times higher than that of pure -Fe2O3 and 5 times higher than that of pure ZnO towards 2000 ppm C2H5OH at an operating temperature of 350 C. Moreover, the response rate was very quick with response time within 30 s. Finally, the mechanism for the improvement in the gas sensing property was discussed.