Study of the factors influencing the immobilization of platinum nanoparticles on multi-walled carbon nanotubes by a polyol process

The immobilization of platinum (Pt) nanoparticles on the surface of multi-walled carbon nanotubes (MWCNTs) was carried out by a polyol process, with hydroxyl (-OH), carboxyl (-COOH) and carbonyl (C = O) groups on the MWCNTs surfaces formed by an acidic oxidation treatment serving to bind the Pt nanoparticles. The resulting composite nanostructures were characterized through transmission electron microscopy and X-ray diffractometry. Pt nanoparticles that formed on the surfaces of the MWCNTs (Pt/MWCNTs) had an average diameter of similar to 4 nm. The aggregation and size of these Pt nanoparticles were influenced by the concentration of polyvinylpyrrolidone (PVP, used as a stabilizer), the molecular weight of the PVP and the molar ratio of the reducing agent to Pt ions in the reaction medium. In addition, the concentration of the Pt source (H2PtCl6) had a profound influence on the immobilization of the Pt nanoparticles on the surfaces of the MWCNTs. When PVP was present in the solution, the coverage and number of Pt nanoparticles increased with increasing Pt source concentration. However, the degree of aggregation of Pt nanoparticles on the surface of MWCNTs was also increased.