Controlled synthesis of core/shell magnetic iron oxide/carbon systems via a self-template method

Abstract

A sol-gel assembly process was developed for the synthesis of magnetic core/carbon shell materials with porous networks. Fe(CO)₅ was assembled into the pore channels of mesoporous silicavia a sol-gel method at 18 °C, by using the block copolymer F127 as the template and Fe(CO)₅ as an additional precursor. At this temperature, the magnetic precursor Fe(CO)₅ was pre-organized into hydrophobic cores of micelles by self-assembly of F127. In the subsequent carbonization of the assembly under an Ar atmosphere, Fe(CO)₅ transformed into magnetic nanoparticles and surfactant F127 transferred into carbon shells enveloping the magnetic nanoparticles, forming magnetic iron oxide core/carbon shell structures. The removal of the silica with 5% HF acid resulted in the core/shell nanoporous composite. The obtained system demonstrates a saturation magnetic value of 3 emu g⁻¹ as well as a high surface area (98 cm² g⁻¹) and pore volume (0.21 m³ g⁻¹), which would benefit its potential applications as adsorbents and catalysts, or applications in targeted drug delivery systems. This facile strategy would provide an efficient approach for tailoring core/shell porous materials with desired functionalities and structures by adjusting precursors and structure-directing agents.