Gas-sensing and mechanism of α-Fe₂O₃ nanowires synthesized by thermal oxidation

The traditional gas-sensitive materials has been difficult to meet the increasing demands in gas monitoring because of the more and more serious problems in domestic gas, vehicle exhaust and industrial emissions. a-Fe₂O₃ nanostructures become one of the most important gas-sensitive materials due to its good thermal stability, high selectivity, non -toxic, anti -corrosive, environmental friendliness and low price. Herein, single monoclinic crystalline a-Fe₂O₃nanowires are synthesized by simple thermal oxidation. a-Fe₂O₃ nanowires have an average 20-50 nm in diameters, and a length up to 1-5 μm. The optimum working temperature is about 383 ℃ and sensitivity is up to 2.4 in 50 ppm ethanol atmosphere. The corresponding recovery and response time were 13 s and 6 s, respectively. Gas sensing mechanism in ethanol for the sensor based on a-Fe₂O₃ nanowires are surface resistivity controlled type.