The stability number as a metric for electrocatalyst stability benchmarking

Simon Geiger, Olga Kasian, Marc Ledendecker, Enrico Pizzutilo, Andrea M. Mingers, Wen Tian Fu, Oscar Diaz-Morales, Zhizhong Li, Tobias Oellers, Luc Fruchter, Alfred Ludwig, Karl J.J. Mayrhofer, Marc T.M. Koper, Serhiy Cherevko

Research output: Contribution to journalArticlepeer-review

526 Scopus citations

Abstract

Reducing the noble metal loading and increasing the specific activity of the oxygen evolution catalysts are omnipresent challenges in proton-exchange-membrane water electrolysis, which have recently been tackled by utilizing mixed oxides of noble and non-noble elements. However, proper verification of the stability of these materials is still pending. Here we introduce a metric to explore the dissolution processes of various iridium-based oxides, defined as the ratio between the amounts of evolved oxygen and dissolved iridium. The so-called stability number is independent of loading, surface area or involved active sites and provides a reasonable comparison of diverse materials with respect to stability. The case study on iridium-based perovskites shows that leaching of the non-noble elements in mixed oxides leads to the formation of highly active amorphous iridium oxide, the instability of which is explained by the generation of short-lived vacancies that favour dissolution. These insights are meant to guide further research, which should be devoted to increasing the utilization of highly durable pure crystalline iridium oxide and finding solutions to stabilize amorphous iridium oxides.

Original languageEnglish
Pages (from-to)508-515
Number of pages8
JournalNature Catalysis
Volume1
Issue number7
DOIs
StatePublished - 1 Jul 2018
Externally publishedYes

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