Nanoparticles Fabricated on Carbon Nanofibers Through Dual-Solvent-Assisted Microwave Carbothermal Shock

Metal nanoparticles supported on carbon nanofibers (CNFs) are promising for catalytic and electrochemical applications, but controlling their size, dispersion, and phase during rapid thermal processing remains challenging. Here, we report a dual-solvent microwave carbothermal shock (CTS) method for producing Cu- and Ni-containing nanostructures on CNFs under ambient-pressure conditions. Ethanolic metal nitrate precursors were deposited on pristine CNFs, and hexane was introduced as an antisolvent before microwave irradiation. At 0.05 M Cu(NO₃)₂, hexane addition decreased the mean Cu-containing particle diameter from 50 ± 20 nm to 33 ± 12 nm and improved dispersion. Varying precursor concentration further altered particle morphology and aggregation. For Ni, single-solvent processing yielded aggregated nanoparticles averaging 43 ± 16 nm, whereas dual-solvent processing produced a dense carbon nanotube network with an apparent mean filament diameter of 20 ± 7 nm. Microscopy and elemental mapping supported the association of Ni-containing particles with the nanotubes. X-ray diffraction identified crystalline face-centered cubic Cu and Ni, while X-ray photoelectron spectroscopy indicated oxidized surface species. Hexane may additionally supply carbon during Ni-assisted nanotube growth, although its contribution requires confirmation. This approach provides a rapid, tunable route to supported metal nanoparticles and hierarchical carbon nanostructures without continuous external inert or hydrocarbon gas flow.