Electrochemical Synthesis of Carbon Fluorooxide Nanoparticles from 3C-SiC Substrates

Chemical nature of products, formed during electrochemical dissolution of polycrystalline 3C-SiC substrate in HF:ethanol mixture, was studied by means of FTIR spectroscopy, temperature-programmed desorption mass spectrometry (TPD-MS), H-1, C-13, and F-19 NMR (solution as well as MAS), XPS, AFM, and other characterization methods. Simultaneous formation of two major products, porous SiC and carbon fluorooxide (CFO) nanoparticles (NPs) with sizes of 1-10 nm, is described. CFO NPs easily dissolve in polar organic solvents (ethanol, CH2Cl2, etc.); their solutions demonstrate intense yellowish-green photoluminescence under UV excitation. A model of the CFO chemical structure based on relatively small graphene domains interconnected with partially fluorinated hydrocarbon groups and terminated by carboxylic acid (-CO2H), ethyl ester (-CO2C2H5), perfluorinated functional groups, and polycarboxylated alkyl chains is proposed. Presence of carboxylates allows easy functionalization of the CFO NPs via amide chemistry. In particular, grafting of octadecyl groups makes CFO NPs soluble in hydrocarbons.