Understanding the formation of nanorods on hematite (α-Fe2O3) in the presence of surfactants: A molecular dynamics simulation study

Abstract

Molecular dynamics (MD) simulations are applied to understand the morphology of adsorbed surfactants and formation of nanorods on (010) surface of hematite (α-Fe2O3). Three different surfactants are used, anionic - Sodium dodecyl sulphate (SDS), non-ionic - Octyl glucoside (OGA) and cationic - Hexadecyltrimethylammonium bromide (HDAB). The analysis has suggested that SDS has highest interaction among all the surfactants. As a result, it leads to the formation of nanorods on (010) plane of α-Fe2O3. The surfactant aggregates are formed in HDAB and OGA. These two surfactants differ in their tail length. As a result, there would be differences in hydrophobic interaction among the tails of the HDAB and OGA. There is a high tendency for the tails of the HDAB to aggregate and form spherical morphology on the α-Fe2O3 surface. On the other hand, a weak coupling is observed among the carbon atoms in the tails of the OGA surfactants. Hence, the absorption of OGA effectively evolves as the simulation proceeds. The differences in the morphology of different categories of surfactants lead us to explain the formation of nanorods for α-Fe2O3 nanoparticles (NPs).