Neuron-like polyelectrolyte-carbon nanotube composites for ultra-high loading of metal nanoparticles

We report a simple protocol for the fabrication of multiwalted carbon nanotubes (MWCNTs) with a neuron-like structure for loading ultra-high densities of metal nanoparticles (NPs). The MWCNTs were initially coated with an anionic polyelectrolyte (PE), polystyrene sodium sulfonate (PSS), using a noncovalent interaction (CNT/PSS). The neuron-like structures were fabricated through the stepwise assembly of both the positively charged poly(allylamine) hydrochloride (PAH) and negatively charged poly(acrylic acid) (PM) in a non-stoichiometric ratio on the CNT/PSS as a template. After three coatings with the PEs, the obtained neuron-shaped CNTs were used as a support for loading a high density of multi-metallic NPs. Moreover, a unique characteristic, tunable and side specific growth of the metal NPs, was also observed. Our neuron-like structures with high loadings of multi-metallic NPs were demonstrated to be catalytic materials for the conversion of 4-nitrophenol to 4-aminophenol and as convenient surface-enhanced Raman scattering substrates for biological tags and molecular detection.