NO(2) Selective Sensor Based on α-Fe(2)O(3) Nanoparticles Synthesized via Hydrothermal Technique

In the present work, hematite (α-Fe(2)O(3)) nanopowders were successfully prepared via a hydrothermal route. The morphology and microstructure of the synthesized nanopowders were analyzed by using scanning and transmission electron microscopy (SEM and TEM, respectively) analysis and X-ray diffraction. Gas sensing devices were fabricated by printing α-Fe(2)O(3) nanopowders on alumina substrates provided with an interdigitated platinum electrode. To determine the sensor sensitivity toward NO(2), one of the main environmental pollutants, tests with low concentrations of NO(2) in air were carried out. The results of sensing tests performed at the operating temperature of 200 °C have shown that the α-Fe(2)O(3) sensor exhibits p-type semiconductor behavior and high sensitivity. Further, the dynamics exhibited by the sensor are also very fast. Lastly, to determine the selectivity of the α-Fe(2)O(3) sensor, it was tested toward different gases. The sensor displayed large selectivity to nitrogen dioxide, which can be attributed to larger affinity towards NO(2) in comparison to other pollutant gases present in the environment, such as CO and CO(2).