Highly mesoporous α-Fe₂O₃nanostructures: preparation, characterization and improved photocatalytic performance towards Rhodamine B (RhB)

Abstract

Single-crystalline porous hematite nanorods and spindle-like nanostructures were successfully synthesized by a low temperature reflux condensation method. Two different iron sources, namely, FeCl3 center dot 6H(2)O and Fe(NO3)(3)center dot 9H(2)O, were hydrolyzed in the presence of urea to selectively prepare nanorods and spindle-like nanostructures. Initially, the akagenite phase was obtained by refluxing the precursor for 12 h and then the as-prepared akagenite nanostructures were transformed to porous hematite nanostructures upon calcination at 300 degrees C for 1 h. The shape and the aspect ratio of the 12 h refluxed sample was retained even after calcination and this shows the topotactic transformation of the nanostructure. TEM and HRTEM investigations have shown the porous nature of the prepared sample. Brunauer-Emmett-Teller and Barret-Joyner-Halenda measurements have shown a large surface area and distribution of mesopores in the nanorods sample. The photocatalytic activity of the prepared nanostructures towards RhB has reflected this variation in the pore size distribution and specific surface area, by showing a higher activity for the nanorods sample. Magnetic studies by VSM have shown a weak ferromagnetic behaviour in both the samples due to shape anisotropy.