Polymeric p-n Nanojunctions: Formation and Electrochemical Properties of C60-Pd@Polypyrrole Core-Shell Nanoparticles

A simple approach to the synthesis of core-shell C-60-Pd@polypyrrole nanoparticles is described. The nanoparticles were characterized by using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray fluorescence, infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Special attention was devoted to the electrochemical properties of the C-60-Pd@polypyrrole nanoparticles. Thin films formed from these nanoparticles exhibited a large potential range of electrochemical activity. Oxidation of the polypyrrole component was observed at positive potentials. Reduction of the C-60-Pd inner core in a negative potential range depended on the thickness of the outer polypyrrole layer. With a thin outer shell (less than approximately 20nm), electrons and counter ions can be transported through it, enabling reduction of the inner C-60-Pd phase. Owing to the different redox properties of the two nanoparticle components, these systems represent spherical p-n nanojunctions.