Ripening of silver nanoparticles on carbon nanotubes

An electrostatic-force-directed-assembly technique was used to coat multiwalled carbon nanotubes (MWCNTs) with aerosol Ag nanoparticles produced from a mini-arc plasma source. The deposition of Ag nanoparticles onto CNTs was confirmed by transmission electron microscopy (TEM), high-resolution TEM, scanning electron microscopy, and X-ray photoelectron spectroscopy. Ripening of Ag nanoparticles on CNTs was observed via successive TEM imaging after heating the nanoparticle-nanotube hybrid structures in air to three different temperatures ranging from 100 degrees C to 300 degrees C. With temperatures at and above 200 degrees C, the areal density of Ag nanoparticles decreased and the average particle size increased. In particular, migration and coalescence of Ag nanoparticles have been observed at this relatively low temperature, which suggests a van der Waals nanoparticle-nanotube interaction