Particle size determination from magnetization curves in reduced graphene oxide decorated with monodispersed superparamagnetic iron oxide nanoparticles

Abstract

Reduced graphene oxide (RGO) decorated with superparamagnetic iron oxide nanoparticles (SPION) is a novel composite nanomaterial with a myriad of promising applications. However, processes such as the fast and simple synthesis of non-agglomerated monodispersed SPION on RGO and the accurate characterization of particle size distributions remain challenging. Here we present how to solve these two problems. Firstly, we introduce a new microwave-assisted synthesis of stabilized SPION on RGO which is fast, simple and up-scalable but at the same time renders well dispersed SPION with narrow size distributions. The coverage of the RGO flakes with SPION is extensively tuned and the results are compared with a non-stabilized microwave-assisted method. Secondly, we implement an accurate method for the determination of particle size distributions from magnetization curves in RGO-SPION composite nanomaterials. This method is applied to the prepared composites with different particle size distributions, degrees of particle agglomeration and coverage of the RGO flakes. The influence of sample characteristics in the size determination method is discussed and the results are compared with the values obtained from transmission electron microscopy (TEM) and X-ray diffraction (XRD), showing that the method is well suited for these and potentially other types of superparamagnetic composite nanomaterials.