Solvent dependent dispersion behaviour of macrocycle stabilized cobalt nanoparticles and their applications

Abstract

Cobalt nanoparticles have been prepared by using amine phthalocyanine as a stabilizing agent in one step. The stabilized nanoparticles were characterized by UV-vis, FTIR, Raman, TEM and AFM. The stabilised cobalt nanoparticles have a spherical shape with an average diameter of 3 nm when dispersed in DMSO solvent, whereas they form an interconnected pearl-chain like structure on dispersion in ethanol. The formation of the pearl-chain structure is due to the magnetic dipolar interaction between the neighbouring particles. AFM images showed higher roughness for the chain like structure than the dispersed particles. The cobalt nanoparticles dispersed in two different solvents were studied as substrates for surface enhanced Raman spectroscopy (SERS) and the electrocatalytic oxygen reduction reaction. SERS studies with the chain-like cobalt nanoparticles as a support showed more than 100 times enhancement in the Raman peak intensities for dyes compared to the dispersed structures. In addition, the stabilized nanoparticles coupled with CNTs dispersed in DMSO showed better electrocatalytic activity than in alcohol because of the blocking behaviour and smaller surface area of the pearl-chain structure of nanoparticles in alcohol.