A review article by Masanori Inaba et al. has been published in the International Journal of Hydrogen Energy.
Achieving net-zero greenhouse gas emissions by 2050 will require the widespread adoption of low-carbon hydrogen production technologies. Proton exchange membrane (PEM) water electrolysis uses electricity to split water into hydrogen and oxygen and is regarded as a promising technology for producing “green hydrogen”, particularly when powered by electricity from renewable energy sources.
For the large-scale deployment of PEM water electrolysis, it is important to accurately estimate both the cost of hydrogen production and the amount of iridium (Ir), a scarce metal used as a catalyst, that will be required. Such estimates require technologies capable of quantitatively predicting not only the performance of electrolyzer cells and their constituent materials, but also their degradation and associated performance losses during long-term operation.
For platinum (Pt)-based catalysts used in PEM fuel cells, extensive research has been conducted on catalyst degradation mechanisms and on models for predicting performance losses based on these mechanisms. Review articles have also systematically summarized the findings accumulated through these studies. In contrast, although research on the degradation of iridium oxide catalysts used in PEM water electrolysis has advanced, there has been no comprehensive review linking mechanistic understanding of catalyst degradation with the modeling of performance evolution and lifetime prediction.
Against this background, this review provides an overview of the latest insights into the degradation of iridium oxide catalysts and summarizes recent advances in degradation modeling, while highlighting key challenges and future research directions.
This review is expected to contribute to a deeper understanding of iridium oxide catalyst degradation mechanisms and to advances in lifetime prediction, ultimately supporting the development of more efficient and durable PEM water electrolysis technologies.
Title: Toward Modeling and Mechanistic Understanding of Iridium Oxide Catalyst Degradation in PEM Water Electrolysis
Authors: Inaba, M., Watanabe, T., Kodama, K.
Journal Name: International Journal of Hydrogen Energy
Published: May 15, 2026