Preparation of Carbon-Based Catalysts from Nitrogen-Containing Aromatic Polymers

Abstract

Carbon-based, non-precious-metal catalysts for the oxygen reduction reaction were prepared from polyimides, polyamides, and azoles, by pyrolysis at 900ºC under flowing N2. The catalytic activity for electrochemical oxygen reduction was evaluated by the onset potential, measured at a current density of -2 μA cm-2. Pyrolyzed polymers with high N content showed higher onset potentials. In particular, one catalyst derived from azole (Az5) had an onset potential of 0.82 V, despite being prepared without the use of any metals. Additionally, a catalyst prepared by multistep pyrolysis of polyamide mixed with FeCl2 had high N content and high oxygen reduction activity, with an onset potential of 0.95 V. A membrane electrode assembly prepared using this catalyst had an open circuit voltage of 0.99 V, and a maximum output of 0.48 W cm-2.