Pyrolysis of Copper Phthalocyanine as Non-noble Metal Electrocatalysts for Oxygen Reduction Reaction

We investigated the relationship between oxygen reduction reaction (ORR) activity and the pyrolysis temperature (650–850 °C) of CuPc in alkaline solution. The highly active sites were formed through the decomposition of CuPc or Cu-N₄ structure after releasing 4-nitrophthalonitrile. Cu-N_x incorporated with carbon were the main active sites. The XPS measurement results show that, at lower temperature, the contents of pyridinic-N and pyrrolic-N account for the most of the total N. As the temperature is higher than 750 °C, the content of graphitic N (26.11%) increases and pyridinic-N (58.81%) becomes the dominant specie. When the temperature is higher than 850 °C, the content of graphitic N increases remarkably and becomes the dominant species. Moreover, the specific surface areas decrease with increased pyrolysis temperature. Benefiting from the synergistic effect, the pyrolysis temperature at 750 °C of CuPc displays superior electrocatalytic properties. The obtained results reveal that the fabricated non-noble metal catalysts can be used as low-cost, efficient catalyst for water splitting ORR in metal-air batteries and fuel cells.