An Innovative and Efficient Low Temperature Hydrothermal-Calcination Process for β-FeOOH Nanorods and Hollow-Structure α-Fe2O3 Magnetic Nanorods Exclusively Utilizing FeCl3 in an Alcohol-Containing Aqueous Solution

A facile low temperature hydrothermal-calcination approach was developed for the fabrication of β-FeOOH nanorods (NRs) and hollow-structure α-Fe₂O₃ magnetic nanorods (MNRs), and the products were characterized using SEM, TEM, XRD and VSM techniques. To achieve smaller-sized β-FeOOH NRs, the effects of Fe³⁺ concentration, the volume ratio of ethanol to water in solution, hydrothermal temperature, and hydrothermal time on the structure of the precursors were systematically investigated, and the nanorods with an average length 104 nm and diameter 36 nm were fabricated at hydrothermal temperature of 100 °C for 2 h using 0.15 M ferric chloride hexahydrate in 50% ethanol solution. Subsequently, the hollow-structure α-Fe₂O₃ MNRs with an average length of 67 nm, diameter of 20 nm, and thickness of 5 nm were successfully obtained via the calcination process at 400 °C for 2.5 h for versatile applications.