The effect of synthesis conditions on the growth of carbon nanofilaments using intermetallic copper-tin catalysts

Abstract

We report for the first time the synthesis of carbon nanofilaments using intermetallic Cu–Sn catalysts. The synthesis was achieved by the catalytic decomposition of C2H2 over a mixture of SnO2 and CuO particles. Also, we have investigated the effect of synthesis conditions on the morphology of carbon nanofilaments and the role of Cu–Sn catalysts in the growth mechanism. The weight ratio of SnO2 and CuO determined the phase of the Cu–Sn intermetallic compound. Favorable growth of carbon nanofilaments was observed at a weight ratio of approximately 1:2, which induces the formation of intermetallic Cu41Sn11 nanostructures. Structures observed at different synthesis pressures and temperatures included carbon nanofibers, carbon nanotubes (CNTs), and catalyst-filled CNTs. This morphological change of carbon nanofilaments was because of the change in C2H2 concentration in the reactor and the phase change of the Cu41Sn11 nanostructures. The observation of the growth of carbon nanofilament with increasing synthesis time confirmed the evolution of intermetallic Cu41Sn11 catalysts and the tip-growth mechanism of carbon nanofilaments. This synthesis methodology could be extended for similar syntheses using Sn-based alloy catalysts and direct growth of carbon nanofilaments on 3D substrates such as carbon fiber papers and a Cu foam, showing its potential for practical applications.