Electrochemical and sensing properties of α-Fe2O3 nanoparticles synthesized using hydrothermal method at low reaction temperature

In this work, iron oxide nanoparticles (α-Fe2O3 NPs) were synthesized by hydrothermal method using iron (III) acetylacetonate as a precursor. The annealing process played a significant role in the change of crystallite size and morphology of nanoparticles. The X-ray diffraction analysis confirmed the rhombohedral α-Fe2O3 crystal structure with preferential orientation along (104) plane. Scanning electron microscopy and transmission electron microscopy images exhibited the cubic structure and the SAED pattern showed the polycrystalline nature of the nanoparticles. The Raman and FTIR spectra further confirmed the formation of Fe and O vibration modes. The optical reflection edges shifted toward higher wavelength with the increase in reaction temperatures and bandgap decreased from 2.88 to 2.74 eV. The Brunauer–Emmett–Teller results showed that the large surface area 218.6 m2/g for FeC6 sample. The hysteresis loop was studied by vibrating sample magnetometer and it exhibited a ferromagnetic behavior. The cyclic voltammetry measurements exhibited a high specific capacitance value 1074 Fg−1 at a scan rate of 10 V. At room temperature, the ammonia-sensing properties of α-Fe2O3 NPs were examined. When compared with other gases, α-Fe2O3 NPs were found to have high selectivity toward ammonia. The sensor based on cubic-like NPs had a good response and recovery times with better selectivity to NH3. The results of the experiments clearly revealed that α-Fe2O3 NPs were used as a good sensing material in the production of NH3 sensors.