Controlling the density and site of attachment of gold nanoparticles onto the surface of carbon nanotubes

► Mild acid created functional groups preferably on the ends of carbon nanotubes. ► Strong acid created functional groups on the side walls of carbon nanotubes. ► Concentration of functional groups is directly proportional to oxidation time. ► Gold nanoparticles are bonded to ends and sidewalls of carbon nanotubes.