Synthesis of carbon nanofibers using bimetallic nickel-palladium nano catalysts and evaluation of charge storage capacity

Metal-nanoparticle (NP) catalysts play a crucial role in the chemical vapor deposition synthesis of various nanomaterials, such as nanotubes, nanofibers, and nanowires. The alloying of different metal elements offers the potential for achieving higher growth rates and improving catalyst performance and longevity. However, the precise synthesis of small and uniform metal NPs with the desired composition remains challenging due to theoretical limitations, notably the Hume-Rothery rule. In this study, nickel (Ni)-palladium (Pd) alloy NPs were successfully synthesized via the reverse micelle method, resulting in NPs characterized by consistent and uniform size and shape, with an average diameter of 2.8 nm. The addition of Pd atoms to Ni to form alloy-NPs shifted the growth mode from surface diffusion to bulk diffusion, such that herringbone carbon nanofibers (CNFs) were grown with reduced diameters using CVD. These alloy catalysts maximize the physicochemical properties of herringbone CNFs for electrochemical applications. The increased number of active sites at the CNF edges considerably enhances charge storage while improving charge and discharge rates. Notably, the versatility of the alloy nanocatalysts introduced in this study extends beyond CNF synthesis, as they can also find application in the synthesis of carbon nanotubes and boron nitride nanotubes.