Carbon Deposition from Aromatic Solvents onto Active Intact 3d Metal Surface at Ambient Conditions

Abstract

The process of carbon deposition onto 3d metal surface immersed in aromatic solvents (benzene, toluene, xylene) at ambient conditions was studied for as-prepared magnetic nanoparticles (MNPs) and Fe-based films by thermal analysis, mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, electron microscopy, and energy-dispersive X-ray spectroscopy. The mechanism of the deposition at the interface is likely the heterogeneous Scholl oxidation of the aromatic hydrocarbons, which is the cationic polymerization of the aryl rings. It results in the formation of polycyclic aromatic hydrocarbons (PAH) chemically bonded to the surface of a MNP or thin metallic film. The benzene rings in the polycyclic deposit do not maintain planar aligned structures and do not provide delocalization of the π-electrons in the zone structure. Contrary to the dense graphite layers, the polycyclic layers, although chemically bonded, are not attached tightly to the surface. Such "hairlike" structure of the carboneous deposit might be especially favorable for the applications that imply the enhanced interaction at the surfaces incorporated in the functional matrices (polymeric composites or biosensors). The aromatic chemical nature of the deposit provides strong interaction with most polymers, while its loose structure favors conformational mobility of macromolecular chains at the interface.