Experimental and numerical study of cetyltrimethylammonium bromide (CTAB)-directed synthesis of goethite nanorods

This study demonstrates a facile surfactant-directed approach to prepare goethite (α-FeOOH) nanorods in aqueous solution at room temperature. The obtained α-FeOOH nanorods have a diameter of ∼20 nm and length up to 300 nm. Various experimental parameters have been investigated, such as surfactants, solution pH, and reaction temperature. It is observed that the surfactant, cetyltrimethylammonium bromide (CTAB), plays a key role in the growth of goethite nanorods at ambient conditions. The final product can be purified using diluted hydrochloric acid (HCl) to remove particles of other shapes. Molecular dynamics (MD) method is used to understand the underlying principles governing particle growth through the analysis of the interaction energies between crystal surfaces and surfactant molecules. The simulation results indicate that CTAB can strongly interact with {100}, {010}, and {110} planes, which benefits the growth of nanorods along [001] direction. Such simulations can provide useful information for the synthesis and shape control of other metal oxide materials.