Self-assembly of colloidal gamma-Fe2O3 and FePt nanoparticles on carbon nanotubes by dip-coating process.

The chemically synthesized colloidal gamma-Fe2O3 and FePt nanoparticles (NPs), with the diameter of approximately 10 nm and approximately 4 nm, respectively, adsorbed and assembled on the surface of carbon nanotubes (CNTs) by dip-coating process, through van der Waals interaction between NP and CNT. Repeating the steps of dip-coating and removing the surfactants from NPs significantly increased the amount of NPs as forming multilayers on the CNT. In addition, the electrochemical activities of FePt/CNTs for methanol oxidation were investigated for the potential application as catalysts of direct methanol fuel cells.