Pyrolysis of Iron-Containing Polyanilines under Micropore Generation Control: Electrocatalytic Performance in the...

Pyrolyzed iron-containing polyaniline (C-Fe-PANI) is one of the most promising candidates as a non-precious metal based electrocatalyst for oxygen reduction reaction (ORR). Although the ORR activity depends on the surface area arisen from pyrolysis-generated micropores on C-Fe-PANI particles, the micropore generation is hindered by pyrolysis-formed iron nanoparticles (Fe NPs) embedded inside C-Fe-PANI particles. Here, we demonstrate the pyrolysis of iron-containing PANIs under suppression of micropore-generation hindrance by blocking the Fe NPs formation. The higher-molecular-weight (MW: 100,000) PANI was dispersed in an FeCl₃ solution before pyrolysis for preventing FeCl₃ penetration inside PANI particles. As a result, as compared to the case of lower-MW (5,000) PANI, the Fe NPs formation was more suppressed inside catalyst particles to give 1.9 (1.8) times micropore volume (specific surface area), leading to a 11 % higher current density in ORR electrocatalytic performance test in acidic media.