Optical, spectroscopic and fiber optic gas sensing of potassium doped α-Fe2O3 nanostructures

Nanocrystalline pure and potassium doped α-Fe2−x KxO3−δ (x = 0.03, 0.05) fiber optic gas sensors are proposed for sensing acetone, ethanol, methanol, and ammonia at room temperature. The nanostructured pure α-Fe2O3 and potassium doped α-Fe2−x KxO3−δ (x = 0.03, 0.05) were synthesized by conventional co-precipitation method and crystallite sizes were determined to be 6.02 nm for pure, 5.79 nm for 3%K-Fe2O3 and 3.97 nm for 5%K-Fe2O3. Synthesized nanostructures were characterized using characterization tools such as powder X-Ray Diffraction (XRD) for Structural phase composition, Fourier Transform Infrared Spectroscopy (FTIR) for functional group analysis and Scanning Electron Microscopy (SEM) for surface morphology, Energy-dispersive X-ray spectroscopy (EDX) for elemental analysis. UV–Vis spectroscopy showed optical characteristic properties exhibiting significant variation in absorbance for 5%K-Fe2O3. The gas sensitivity and selectivity characteristics were investigated for pure and doped materials. Time response of 5%K-Fe2O3 for all gases was taken. 5%K-Fe2O3 showed good gas selectivity and higher sensitivity towards acetone gas and gave relatively faster response. These substantiated the influence of potassium doping in α-Fe2O3 nanostructure.