Facile fabrication of metal oxide hollow spheres using polydopamine nanoparticles as active templates

Abstract

A facile method of fabricating metal oxide hollow spheres using polydopamine (PDA) nanoparticles as active templates is reported. Monodisperse PDA nanoparticles were prepared by the polymerization of dopamine in Tris buffer solution containing various amounts of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO). The diameter of the resultant PDA nanoparticles decreased from about 180 to 80 nm with an increase of PEO-PPO-PEO concentration from 0 to 1.25 mg mL-1. The active groups of PDA and also the PEO-PPO-PEO adsorbed on the PDA spheres can chelate with various metal ions. It was found that when PDA spheres with diameter below 100 nm were used as templates, diverse metal oxide hollow spheres like CeO2, NiO and Cr2O3 could be obtained after calcination, demonstrating the diversity of this method for fabricating various metal oxide hollow spheres.