Synthesis, characterization, and comparative gas-sensing properties of Fe2O3 prepared from Fe3O4 and Fe3O4-chitosan

Abstract In this paper, Fe 3 O 4 and chitosan (CS)-coated Fe 3 O 4 nanoparticles were synthesized via co-precipitation method and subsequent covalent binding of CS onto the surface for functionalization, respectively. Characterization of the crystal structures and morphologies of as-synthesized nanoparticles by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy demonstrated that Fe 3 O 4 had a cubic spinal structure with irregular shapes and average diameters of 10–20 nm. The surface states and magnetic properties of Fe 3 O 4 -CS nanoparticles were characterized by Fourier transform infrared spectra and vibrating sample magnetometry. Results showed that Fe 3 O 4 -CS nanoparticles possessed super-paramagnetic properties, with saturated magnetization up to 60 emu/g. In addition, Fe 3 O 4 and CS-coated Fe 3 O 4 nanoparticles were used in the fabrication of α-Fe 2 O 3 based gas sensors. Gas sensing measurements revealed that the α-Fe 2 O 3 gas sensor prepared from Fe 3 O 4 -CS had a better response to H 2 , CO, C 2 H 5 OH, and NH 3 compared with the device prepared from pristine Fe 3 O 4 . Furthermore, the α-Fe 2 O 3 sensor prepared from Fe 3 O 4 -CS nanoparticles exhibited the highest response to CO among the test gases, suggesting that it has great potential for practical applications in environmental monitoring.