The effect of copper on the multiple carbon nanofilaments growths by the methane decomposition over the oxidized diamond-supported nickel\u2013copper bimetallic catalyst

Abstract

To clarify the indispensable parameters for the multiple carbon nanofilaments (CNFs) growths, in other words, having a unique Octopus-like morphology consisting of the Marimo-like carbon (MC), we have systematically studied to synthesize the MC by the decomposition of methane using oxidized diamond-supported Ni–Cu bimetallic catalysts. We discovered that a Cu addition of 20 wt.% by weight and a growth temperature in the region of 550 °C to 600 °C resulted in many CNF forms from a single catalyst particle, specifically the "Octopus-like" morphology of CNFs. We also discovered that the several CNFs forms might occur from the carbon dissolved in the sintered catalyst particles. We described a model process of the unique structure formation. We expect that the Octopus-like CNFs growth gives enough space volume in the MC for a mass transfer, consequently, it should contribute to realizing a higher power generation performance of a polymer electrolyte fuel cell (PEFC) although under a higher-voltage generation region.