Hydrothermal synthesis of α-FeOOH (1D) nanorods and their transition to α-Fe2O3 (0D): an efficient photocatalyst in neutralizing hazardous organic dyes

Abstract

α-FeOOH (goethite) with a nanorod morphology has been synthesized successfully by a hydrothermal method, and further calcinated (6 h at 520 °C) to obtain α-Fe₂O₃ (hematite) nanoparticles of spherical shape morphology. The synthesized α-FeOOH and α-Fe₂O₃ nanoparticles were subjected to various characterization techniques (X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, liquid chromatography with mass spectrometry (LCMS), dynamic light scattering (DLS) and zeta potential (ZP), thermogravimetry analysis (TGA), differential thermal analysis (DTA), X-ray photoelectron spectrometer (XPS), N₂ adsorption–desorption isotherms (BET), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDAX) and transmission electron microscopy (TEM)). Meanwhile, the as-synthesized α-FeOOH and α-Fe₂O₃ nanoparticles were used to degrade hazardous organic cationic dyes such as brilliant green (BG) and rhodamine B (RhB) under sunlight. It was observed from the study that BG (96%, 110 min) and RhB (93%,90 min) show responsive degradation in the presence of α-FeOOH nanorods. Besides this, 99% (100 min) and 99.4% (80 min) BG and RhB get degraded using α-Fe₂O₃ nanoparticles, respectively. Overall, α-Fe₂O₃ nanoparticles were a more prominent photocatalyst for the degradation of BG and RhB than α-FeOOH nanorods.