Highly sensitive and selective butanol sensors using the intermediate state nanocomposites converted from beta-FeOOH to alpha-Fe2O3

Highly sensitive and selective Fe-based gas sensors have been developed by intermediate state nanocomposites where Quasi-Amorphous Intermediate Phase (QUAIPH) and alpha-Fe2O3 co-exist converting from fusiform beta-FeOOH. TGA, SEM, TEM, XRD, FTIR, BET and XPS have been used to characterize the intermediate state nanocomposites. Experiment results reveal that the highest gas sensing performance towards n-butanol can be found when the fusiform beta-FeOOH was calcined at 250 degrees C for one-hour, in which crystalline alpha-Fe2O3 and QUAIPH co-exist. The highest response towards 100 ppm n-butanol is 145 which is the highest one for alcohols detection comparing with the reported alpha-Fe2O3 based gas sensors. Besides, the intermediate state nano composites also exhibit high selectivity to n-butanol among common VOCs. At last, the sensing mechanism has been speculated, in which the structural hydroxyls may enrich the alcohols on the surface of the nanocomposites and prominently increase the response and selectivity.