Nanocrystalline hematite α-Fe2O3 synthesis with different precursors and their composites with graphene oxide

The facile wet chemical co-precipitation method was used for synthesis of hematite (alpha-Fe2O3) nanoparticles and nanocomposites with graphene oxide (GO) using ethylenediaminetetraacetic acid (EDTA) and diethylene-triaminepentaacetic acid (DTPA) as different precursor materials. EDTA and DTPA acted as chelating agents to avoid multi nucleation and aggregation of nanoparticles in growth process. For nanocomposite, GO was considered as flexible material with theoretical specific surface area similar to 1000 m(2)/g and better surface functionalization due to presence of oxygen containing functional groups i.e. carboxylic, hydroxyl and epoxides groups at basal edge. The structural analysis of prepared nanoparticles and nanocomposites was conducted by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). XRD confirmed various cell parameters and crystalline structure of prepared particles. The crystallite size was found 5 nm-10 nm. After preparation of nanocomposites of hematite alpha-Fe2O3 (EDTA or DTPA) nanoparticles with GO, they were characterized by Scanning electron microscopy (SEM) and UV-Visible spectroscopy. Current-Voltage (I-V) measurements were also carried out to observe the decrease in resistivity values after mixing with GO. UV-Visible spectroscopy revealed the better photocatalytic degradation of methylene blue (MB) in visible light. Degradation of methylene blue was observed up to 67% with alpha-Fe2O3 (DTPA) @ GO and 86.06% for alpha-Fe2O3 (EDTA) @ GO greater than simple alpha-Fe2O3 (DTPA) 21.2% and alpha-Fe2O3 (EDTA) 36.8% nanoparticles. As a result, synergistic effect of alpha-Fe2O3 (EDTA) @ GO showed better photocatalytic action due to GO layer, it acted as electron acceptor and kept high adsorption properties. Electrostatic bonding in alpha-Fe2O3 (EDTA) @ GO with MB having different functional groups showed the stability of photocatalyst, not to be leached into water. For prolonged time, the charge carrier recombination was suppressed for improved degradation rate of MB in visible light in presence of alpha-Fe2O3 (EDTA) @ GO.