Control of Branching in Ni₃C_1–xNanoparticles and Their Conversion into Ni₁₂P₅Nanoparticles

Abstract

Dendritic Ni3C1–x nanoparticles (NPs) with controlled branching have been synthesized through the thermolysis (230 °C) of nickel acetylacetonate using oleylamine as a reducing agent and 1-octadecene (ODE) as the solvent. Addition of trioctylphosphine (TOP) as a ligand inhibits formation of dendritic shapes and prevents incorporation of C, resulting in spherical Ni NPs. In comparison, when using octadecane (ODA) or trioctylphosphine oxide (TOPO) as the solvent, Ni NPs are obtained at 230 °C that have fewer, larger branches than when using ODE. Higher temperatures are required for incorporation of C from ODA or TOPO into Ni NPs, resulting in Ni3C1–x NPs. Therefore, the allyl group in ODE facilitates formation of Ni3C1–x NPs at lower temperatures. Conversion of dendritic Ni3C1–x NPs into Ni12P5 NPs after adding TOP and heating to 300 °C results in the formation of multiple voids in the branches, rather than yolk-in-shell structures or unfilled single voids observed for spherical NPs.

Monitoring Ligand‐Mediated Growth and Aggregation of Metal Nanoparticles and Nanodendrites by In Situ Synchrotron Scattering Techniques

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Controlled Growth of a Hierarchical Nickel Carbide “Dandelion” Nanostructure

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Transition Metal (Fe, Co and Ni) Carbide and Nitride Nanomaterials: Structure, Chemical Synthesis and Applications

“…Similar to cobalt carbide synthesis, Ni 3 C nanoparticles were also generated via a polyol process dispersed by polyvinylpyrrolidone (PVP) in tetraethylene glycol solution . Interestingly, Ni 3 C 1− x nanoparticles could convert to Ni 12 P 5 nanoparticles through the addition of trioctylphosphine (TOP) and heating at 300 °C with multiple voids, the conversion chemical reactions forming void architectures were denoted as the Kirkendall effect . As the author declared, the conversion process may occur in a stepwise fashion through phosphides with intermediates of Ni 3 P and Ni 5 P 2 , and the void formed in the case that outward Ni diffused through the shell faster than the reverse P inward diffusion.…”