High Performance and Durable Anode with 10-Fold Reduction of Iridium Loading for Proton Exchange Membrane Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) technology is especially advantageous for green H-2 production as a clean energy vector. During the water electrolysis process, the oxygen evolution reaction (OER) requires a large amount of iridium (2-3 mg(Ir) cm(-2)) as catalyst. This material is scarce and expensive, representing a major bottleneck for large-scale deployment of electrolyzers. This work develops an anode with 10-fold reduction of Ir loading (0.2 mg(Ir) cm(-2)) compared to what it is used in commercial PEMWE for more than 1000 h. An advanced catalyst based on an Ir mixed oxide (Sr2CaIrO6) is used for this purpose. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) analyses show that the unconventional structure of the reconstructed catalyst can contribute to the reduction of Ir in the catalyst layer. The reconfiguration of the ionomer in the catalyst layer is also observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), results in almost the full coverage of the catalytic layer with ionomer. The results presented herein demonstrate that it is possible to achieve high performance and stability in PEMWE with low Ir loading in the anode without showing significant degradation.

Automated summary

In this study, an anode with reduced iridium loading (0.2 mg) compared to commercial proton exchange membrane water electrolysis (PEMWE) (2-3 mg) was developed, demonstrating high performance and stability for over 1000 hours. An advanced catalyst based on an Ir mixed oxide (Sr2CaIrO6) was used, which has an unconventional structure that contributes to the reduction of iridium in the catalyst layer. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed the reconfiguration of the ionomer in the catalyst layer, resulting in almost full coverage of the catalytic layer with ionomers.