Work

Insight into the effects of the cathode operating potential on the ageing mechanisms of PEMFC single cells’ active layers

Year: 2026

Type: article

Abstract: This study aims to unveil the influence of the cell voltage value on the degradation rate of PEMFC single cell durably operated at constant cell voltages (0.6-0.85 V) under H 2 /Air, with minimal intermediate characterisations to limit the impact of voltage cycling. In these potentiostatic test conditions, no major corrosion of the carbon support of the Pt/C catalyst occurs. Whereas the cathode ECSA losses are rather similar whatever the test conditions, the cathodes have different fates depending on whether the ageing is performed at low or high cell voltage. Low cathode potential (cell voltage) prevents Pt-oxides formation (hence Pt passivation) and minors Pt potential-induced dissolution but favours Pt-redeposition: Oswald ripening is the main process of ECSA loss. High cell voltage enables larger Pt passivation by surface oxides, mitigating both Pt dissolution and redeposition/reduction, hence significantly lowering Oswald ripening; these conditions enhance the formation of carbon surface groups, leading to Pt crystallites migration into agglomerates and related ECSA loss. These carbon surface groups are only minorly oxidised into CO 2 , because Pt-assisted corrosion is unlikely for Pt-oxides. The ORR performance remains high after low potential ageing (the ECSA loss is counterbalanced by the positive Pt nanoparticles-size-effect) and degrades faster after high potential ageing (the ECSA loss is accompanied by rather irreversible Pt-oxides formation after high-potential holds, which results in very depreciated apparent ORR kinetics). One cannot exclude that the different cell voltages experiences lead to different water content of the active layers, this effect probably being second-order compared to that of the potential.

Source: Electrochimica Acta

DOI: 10.1016/j.electacta.2026.149473

Authors: Raphaël Riasse, Laetitia Dubau, Julien Durst, Gaël Maranzana, Marian Chatenet