One-Pot Production of Size-/Shape-Tunable Hydrophobic and Hydrophilic Medium-/High-Entropy Spinel Ferrites

Multimetal nanoparticles, including medium- and high-entropy spinel ferrites (MESF/HESFs), are of significant interest, but large-scale production with high monodispersity remains challenging and poorly documented. Traditional synthesis methods balance simplicity and quality, with thermal decomposition being optimal for scalable, uniform nanoparticle production. However, its utility is limited by costly and sensitive precursors like acetylacetonates and carbonyls, or oleates, which require tedious synthesis, are hard to handle, and are moisture-sensitive, impacting nanoparticle quality. A streamlined one-pot synthesis for multimetal ferrites including MESF/HESFs is introduced in this study that addresses these critical bottlenecks utilizing cheap metal nitrates. The core innovation is the alcoholic hydrolysis of metal nitrates into hydroxides, which enables in situ precursor formation. This approach bypasses intricate precursor preparation and eliminates water from the synthesis, thereby resolving issues with hydrated precursors. The method is highly versatile, producing a broad spectrum of monodispersed multimetal ferrite nanoparticles, from simple binary to MESF/HESFs, and extendable to different metal oxides. The nanoparticles were superparamagnetic at room temperature. The X-ray Rietveld refinement verified that a single cubic spinel phase was present. A fresh nanoparticle surface-functionalization using nitrilotriacetic acid is demonstrated, allowing for the easy transfer of hydrophobic nanoparticles into water directly from the crude reaction mixture.