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

Abstract

Proton exchange membrane water electrolysis (PEMWE) technology is especially advantageous for green H2 production as a clean energy vector. During the water electrolysis process, the oxygen evolution reaction (OER) requires a large amount of iridium (2-3 mgIr 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 mgIr 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.