Morphology of metallic nanoparticles as a function of deposition time in electroless deposition of metal on multi-walled carbon nanotubes

Morphology of silver (or copper) nanoparticles as a function of deposition time was examined in electroless deposition of metal on multi-walled carbon nanotubes (MWCNTs). Silver (or copper) deposited MWCNTs were prepared using successively, surface oxidation, tin-palladium activation, hydrochloric acid-acceleration, and ELD of silver (or copper). The results show that nanoparticles of face-centered cubic silver (or copper) were deposited initially on the interior surface of a MWCNT (~ 50 nm in inner diameter) but later on its exterior surface. The percentage silver (or copper) in the coated MWCNTs increased from 7.0 (6.7) to 28.2 (25.5) wt.% by weight for a deposition time ranging from 3 to 10 min. The average diameter of silver (copper) nanoparticles increased from 1.3 (1.1) to 2.6 (2.3) nm, while the surface area and pore volume decreased from 261 to 144 (81) m²/g and from 1.02 to 0.38 (0.27) cm³/g, respectively. However, there was no silver deposition on the interior surface of a thin-MWCNT (~ 5 nm in inner diameter) observed because the capillarity decreases with decreasing tube diameter.