How to appropriately assess the oxygen reduction reaction activity of platinum group metal catalysts with rotating disk electrode

The sluggish oxygen reduction reaction (ORR) has becoming the bottleneck of largescale implementation of proton exchange membrane fuel cells. However, when it comes to the ORR activity assessing of platinum group metals (PGMs) with rotating disk electrode, the corresponding potential conversion vs. reversible hydrogen electrode, test protocols, and activity calculation processes are still in chaos in many published literatures. In this work, two standard calculation processes for PGM ORR activities are demonstrated, followed by a specification for the usage of reference electrodes. Then a 4-fold discrepancy in ORR activities obtained via different test protocols is found for the same Pt/C, and an average adsorption model and the coverage effects'' are proposed to illustrate the hysteresis loop between negative and positive-going ORR polarization plots. Finally, four motions over appropriate assessment of PGM ORR activity are emphasized, hoping to bring a fair communication platform for researchers from different groups.

Automated summary

The slow oxygen reduction reaction (ORR) has become a bottleneck for the large-scale implementation of proton exchange membrane fuel cells. There is confusion in the assessment of platinum group metals (PGMs) ORR activities, including potential conversion, test protocols, and activity calculation processes. This study demonstrates two standard calculation processes for PGM ORR activities and emphasizes the importance of using reference electrodes for accurate assessment. Additionally, the study highlights the discrepancy in ORR activities obtained via different test protocols and proposes an average adsorption model and coverage effects to explain the behavior of ORR polarization plots.