Superparamagnetic iron oxide nanoparticles (SPIONs) supported on high surface area mesoporous SiO₂ are advanced materials of great interest in catalysis, adsorption and biomedicine. Here we present a new process to prepare SPION/SiO₂ materials by the impregnation and insitu decomposition of Fe(NO₃)₃.9H₂O on mesoporous SiO₂ supports in a 25–50 % mol ethanol + CO₂ mixture at 523 K and 25.0 MPa. γ-Fe₂O₃ nanoparticles (NPs) of average size between 6−9 nm were homogeneously distributed on the supports. NPs deposited into the SBA-15 mesopores but mostly on the external surface of MCM-41. Materials prepared with the highest ethanol content were very homogeneous. Magnetic measurements confirmed the superparamagnetic nature of the materials at room temperature. The process proposed is sustainable and scalable, avoids tedious preparations and the additional high temperature treatment under a controlled atmosphere, as the metal decomposition is performed insitu in the CO₂-expanded liquid mixture.

高表面积介孔SiO ₂上负载的超顺磁性氧化铁纳米颗粒（SPIONs）是在催化，吸附和生物医学领域引起极大兴趣的先进材料。在这里，我们提出了一种新方法，通过在25-50％mol乙醇+ CO ₂混合物中于523 K下将Fe（NO ₃）₃ .9H ₂ O浸渍并在介孔SiO ₂载体上原位分解来制备SPION / SiO ₂材料。和25.0 MPa。了γ-Fe ₂ ö ₃平均尺寸在6-9 nm之间的纳米颗粒（NP）均匀分布在载体上。NP沉积到SBA-15中孔中，但大部分沉积在MCM-41的外表面。用最高乙醇含量制备的材料非常均匀。磁性测量证实了该材料在室温下的超顺磁性。所提出的方法是可持续和可扩展的，避免了繁琐的准备工作，并且避免了在受控气氛下进行额外的高温处理，因为金属分解是在CO ₂膨胀的液体混合物中原位进行的。