Polyaniline-derived Non-Precious Catalyst for the Polymer Electrolyte Fuel Cell Cathode

摘要

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 (E_(1/2)) 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 four-electron reduction, with H_2O_2 yields below 1% (0.4% at 0.4 V). Similarly, the catalyst showed good performance in the hydrogen-air 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.