Constructing magnetic Si-C-Fe hybrid microspheres for room temperature nitroarenes reduction

In this work, we present the first synthesis and characterization of magnetic Si-C-Fe hybrid microspheres and their catalysis in room temperature reduction of 4-nitrophenol as a representative sustainable process of converting environmental pollutants to fine chemicals. The ferrocene-modified polydivinylbenzene (Fc-PDVB) precursor was synthesized by Pt-catalyzed hydrosilylation between the residual vinyl groups on PDVB surface and 1, 1’-bis (dimethylsilyl)ferrocene, where further pyrolysis led to the formation of α-Fe nanocrystals-containing Si-C-Fe hybrid microspheres. The precursor and hybrid microspheres were characterized in terms of transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), BET surface area/porosity, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic properties and MAS solid-state NMR measurements. The ultimate microspherical catalyst exhibited nano- and meso-pores, high specific surface area (i.e., 347.9 m2 g-1) and good ferromagnetic properties. Efficient catalytic activity (TOF: 0.163 s-1), 100% selectivity (to 4-aminophenol) and excellent reusability (with easy separation) have been delivered. The achieved performance outperforms a number of nanomaterials such as supported noble metal particles, composites, monoliths and sheets. We have confirmed by DFT calculations that the activation of 4-nitrophenol via its weak non-covalent interaction with the sp2 carbon domain of Si-C-Fe hybrid microspheres contributed to the superior performance which can be extended to a range of nitrobenzenes.