Half-cell electrode assessments of a crossover-tolerant direct methanol fuel cell with a platinum group metal-free cathode

In this work, a platinum group metal- free (PGM-free) Fe-N-C oxygen reduction reaction (ORR) catalyst derived from metal organic framework precursors (Fe-MOF) is evaluated at the cathode side of a direct methanol fuel cell (DMFC). A wide range of methanol concentrations were used, and the performance of the DMFC using air was evaluated and compared to a commercial Pt/C cathode. We conducted our tests with a custom, integrated H₂ reference electrode that separately provided the anode and cathode overpotentials. This allowed us to perform a Tafel analysis on both electrodes and understand the dominant polarizations involved at the PGM-free cathode and the PtRu/C anode. Overall, we achieved a high cell performance using a Fe-N-C based catalyst under liquid methanol and air operation with a peak power density of 111 mW/cm², where the cathode presented a markedly larger contribution to the voltage loss versus the anode. Additionally, we used nanoscale X-ray computed tomography (nano-CT) to image the Fe-N-C cathode and investigate the ionomer and pore size distributions allowing us to identify areas of improvement for catalyst layer fabrication.