Polyaniline-derived non-precious catalyst for the polymer electrolyte fuel cell cathode

This paper focuses on a new polyaniline-derived non-precious cathode catalyst with high oxygen-reduction activity, verified in electrochemical and fuel cell testing. The rotating disk (RDE) onset and half-wave potential (E1/2) of oxygen reduction were measured at 0.90 V and 0.77 V, respectively. Rotating ring-disk electrode (RRDE) study revealed very good selectivity in the fourelectron reduction, with H₂O₂ yields below 1% (0.4% at 0.4 V). Similarly, the catalyst showed good performance in the hydrogenair fuel cell, even at high cell operating voltages, yielding 0.04 A cm^-2 at 0.80 V and 0.21 A cm^-2 at 0.6 V. Fuel cell life test at a constant voltage of 0.4 V demonstrated promising stability up to 450 hours, generating a current density of approximately 0.32 A cm^-2, a respectable performance for a non-precious cathode catalysts operated on air rather than oxygen. Ex situ characterization pointed to pyridinic-and pyrrolic-nitrogen metal species as likely active ORR sites.