Multiscale simulations of the hydration shells surrounding spherical Fe3O4 nanoparticles and effect on magnetic properties
Iron oxide magnetic nanoparticles (NPs) are excellent systems in catalysis and in nanomedicine, where they are mostly immersed in aqueous media. Even though the NPs solvation by water is expected to play an active role, the detailed structural insight at the nanostructure oxide/water interface is still missing. Here, based on our previous efforts to obtain accurate models of dehydrated Fe3O4 NPs and of their magnetic properties and through multiscale molecular dynamics simulations combining density functional tight binding method and force field (QM/MM), we unravel the atomistic details of the short range (chemical) and long range (physical) interfacial effects when magnetite nanoparticles are immersed in water. The influence of the first hydration shell on the structural, electronic and magnetic properties of the Fe3O4 NP is revealed by high-level hybrid density functional calculations. Hydrated Fe3O4 NPs possess larger magnetic moment then dehydrated ones. This work bridges the large gap between experimental studies on solvated Fe3O4 NPs and theoretical investigations on flat Fe3O4 surfaces covered with few water layers and paves the way for further study of Fe3O4 NPs in biological environments.