In situ reduction of Ag on magnetic nanoparticles with gallic acid: effect of the synthesis parameters on morphology.

Aim: Synthesis of Fe 3 O 4 -Ag composite nanoparticles (NPs) by a new in situ reduction of Ag NPs on the surface of Fe 3 O 4 NPs using gallic acid as a reducing agent. Materials & methods: The influence of process parameters on NP morphology and functionalization was evaluated by means of field-emission scanning/scanning transmission electron microscopy and Fourier-transform IR spectroscopy. Results & conclusion: The synthesis conditions affected the morphology of the obtained NPs, evidence of the formation of polydispersed aggregates, nanoflower-like or nanodumbbell nanocomposites. In particular, well-defined nanodumbbells were obtained in aqueous media, with an NP/gallic acid ratio of 10:1, while the presence of a silica shell did not improve the morphology of Ag NPs nucleated on the Fe 3 O 4 core.