Electrochemical synthesis of metal-polypyrrole composites and their activation for electrocatalytic reduction of oxygen by thermal treatment

This work presents a new approach for synthesis of oxygen reduction catalysts constituted of a transition metal, nitrogen and carbon, by thermal treatment of electrochemically synthesized metal-polypyrrole (M-PPy) composites on glassy carbon electrodes. The synthesis procedure involves immobilization of PPy on glassy carbon followed by dosing of metal (M = Mn, Fe and Co) particles, alternately, by electropolymerization and electrochemical reduction respectively. Electrochemical characterization by cyclic voltammetry (CV) and hydrodynamic rotating disk electrode (ROE) measurements show that the M-PPy composites inherently catalyse the electroreduction of oxygen under acidic conditions. The activity of the composites is significantly augmented when they are heat treated at high temperatures (450-850 degrees C) under a continuous flow of nitrogen. The presence of metallic entities within the M-PPy composite structures and in the structures ensuing after heat treatment was confirmed by energy dispersive X-ray (EDX) analysis. (C) 2011 Elsevier Ltd. All rights reserved.