One-pot synthesis of yolk shell mesoporous carbon spheres with high magnetisation

A simple and novel route for the synthesis of monodisperse yolk-shell magnetic mesoporous carbon spheres (Fe3O4@void@C) via a 'one-pot' strategy for direct carbonisation and etching was developed. The synthesised materials were characterised by XRD, TEM, SEM, FT-IR, EDS, TGA, N-2 sorption, and magnetic susceptibility measurements, and the ideal conditions for the synthesis of the Fe3O4@void@C spheres were systematically investigated. The morphologies and the saturation magnetisation values were observed to be strongly influenced by the composition of the solvent (ethanol-water) and the proportions of TEOS and formaldehyde used in the synthesis. The synthesised materials possessed a large average pore diameter (4.5 nm) and a magnetisation strength (62 emu g(-1)) greater than that of Fe3O4 itself. The performance of Fe3O4@void@C in the adsorption of pyrene was tested in aqueous solution, and fast adsorption rates (approximately 40 min to reach equilibrium) and high adsorption capacities (77.1 mg g(-1)) were observed. In addition, Fe3O4@avoid@C exhibited excellent reusability for the adsorption of pyrene over six adsorption-desorption cycles.